expand errer (!) in a config block - can't process "://"?

I ship an nginx config in a config block, and it trips up helmfile, but is ok with helm (and k8s) itself.
The offender seems to be
return 301 $scheme://$host:$server_port/remote.php/dav;
repositories:
# Stable repo of official helm charts
- name: "movi"
  url: "https://inzmovi.gitlab.io/helm-charts"

releases:
- name: "nextcloud"
  namespace: "nextcloud"
  chart: "movi/nextcloud"
  version: "1.8.2"
  wait: false
  values:
    - nginx:
        enabled: true
        config:
          default: true
          custom: |-
            worker_processes auto;

            error_log  /var/log/nginx/error.log warn;
            pid        /var/run/nginx.pid;

            events {
                worker_connections  1024;
            }

            http {
                include       /etc/nginx/mime.types;
                default_type  application/octet-stream;

                log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                                  '$status $body_bytes_sent "$http_referer" '
                                  '"$http_user_agent" "$http_x_forwarded_for"';

                access_log  /var/log/nginx/access.log  main;

                sendfile        on;
                #tcp_nopush     on;

                keepalive_timeout  65;

                #gzip  on;

                upstream php-handler {
                    server 127.0.0.1:9000;
                }

                server {
                    listen 80;

                    # set max upload size
                    client_max_body_size 10G;
                    fastcgi_buffers 64 8K;
                    # Add headers to serve security related headers
                    # Before enabling Strict-Transport-Security headers please read into this
                    # topic first.
                    #add_header Strict-Transport-Security "max-age=15768000; includeSubDomains; preload;" always;

                    #
                    # WARNING: Only add the preload option once you read about
                    # the consequences in https://hstspreload.org/. This option
                    # will add the domain to a hardcoded list that is shipped
                    # in all major browsers and getting removed from this list
                    # could take several months.
                    add_header Referrer-Policy "no-referrer" always;
                    add_header X-Content-Type-Options "nosniff" always;
                    add_header X-Download-Options "noopen" always;
                    add_header X-Frame-Options "SAMEORIGIN" always;
                    add_header X-Permitted-Cross-Domain-Policies "none" always;
                    add_header X-Robots-Tag "none" always;
                    add_header X-XSS-Protection "1; mode=block" always;

                    # Remove X-Powered-By, which is an information leak
                    fastcgi_hide_header X-Powered-By;

                    # Path to the root of your installation
                    root /var/www/html;

                    location = /robots.txt {
                        allow all;
                        log_not_found off;
                        access_log off;
                    }

                    # The following 2 rules are only needed for the user_webfinger app.
                    # Uncomment it if you're planning to use this app.
                    #rewrite ^/.well-known/host-meta /public.php?service=host-meta last;
                    #rewrite ^/.well-known/host-meta.json /public.php?service=host-meta-json last;

                    # The following rule is only needed for the Social app.
                    # Uncomment it if you're planning to use this app.
                    #rewrite ^/.well-known/webfinger /public.php?service=webfinger last;

                    location = /.well-known/carddav {
                        return 301 $scheme://$host:$server_port/remote.php/dav;
                    }

                    location = /.well-known/caldav {
                        return 301 $scheme://$host:$server_port/remote.php/dav;
                    }

                    # Enable gzip but do not remove ETag headers
                    gzip on;
                    gzip_vary on;
                    gzip_comp_level 4;
                    gzip_min_length 256;
                    gzip_proxied expired no-cache no-store private no_last_modified no_etag auth;
                    gzip_types application/atom+xml application/javascript application/json application/ld+json application/manifest+json application/rss+xml application/vnd.geo+json application/vnd.ms-fontobject application/x-font-ttf application/x-web-app-manifest+json application/xhtml+xml application/xml font/opentype image/bmp image/svg+xml image/x-icon text/cache-manifest text/css text/plain text/vcard text/vnd.rim.location.xloc text/vtt text/x-component text/x-cross-domain-policy;

                    # Uncomment if your server is build with the ngx_pagespeed module
                    # This module is currently not supported.
                    #pagespeed off;

                    location / {
                        rewrite ^ /index.php;
                    }

                    location ~ ^\/(?:build|tests|config|lib|3rdparty|templates|data)\/ {
                        deny all;
                    }

                    location ~ ^\/(?:\.|autotest|occ|issue|indie|db_|console) {
                        deny all;
                    }

                    location ~ ^\/(?:index|remote|public|cron|core\/ajax\/update|status|ocs\/v[12]|updater\/.+|oc[ms]-provider\/.+)\.php(?:$|\/) {
                        fastcgi_split_path_info ^(.+?\.php)(\/.*|)$;
                        set $path_info $fastcgi_path_info;
                        try_files $fastcgi_script_name =404;
                        include fastcgi_params;
                        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
                        fastcgi_param PATH_INFO $path_info;
                        # fastcgi_param HTTPS on;
                        # Avoid sending the security headers twice
                        fastcgi_param modHeadersAvailable true;
                        # Enable pretty urls
                        fastcgi_param front_controller_active true;
                        fastcgi_pass php-handler;
                        fastcgi_intercept_errors on;
                        fastcgi_request_buffering off;
                    }

                    location ~ ^\/(?:updater|oc[ms]-provider)(?:$|\/) {
                        try_files $uri/ =404;
                        index index.php;
                    }

                    # Adding the cache control header for js, css and map files
                    # Make sure it is BELOW the PHP block
                    location ~ \.(?:css|js|woff2?|svg|gif|map)$ {
                        try_files $uri /index.php$request_uri;
                        add_header Cache-Control "public, max-age=15778463";
                        # Add headers to serve security related headers (It is intended to
                        # have those duplicated to the ones above)
                        # Before enabling Strict-Transport-Security headers please read into
                        # this topic first.
                        #add_header Strict-Transport-Security "max-age=15768000; includeSubDomains; preload;" always;
                        #
                        # WARNING: Only add the preload option once you read about
                        # the consequences in https://hstspreload.org/. This option
                        # will add the domain to a hardcoded list that is shipped
                        # in all major browsers and getting removed from this list
                        # could take several months.
                        add_header Referrer-Policy "no-referrer" always;
                        add_header X-Content-Type-Options "nosniff" always;
                        add_header X-Download-Options "noopen" always;
                        add_header X-Frame-Options "SAMEORIGIN" always;
                        add_header X-Permitted-Cross-Domain-Policies "none" always;
                        add_header X-Robots-Tag "none" always;
                        add_header X-XSS-Protection "1; mode=block" always;

                        # Optional: Don't log access to assets
                        access_log off;
                    }

                    location ~ \.(?:png|html|ttf|ico|jpg|jpeg|bcmap)$ {
                        try_files $uri /index.php$request_uri;
                        # Optional: Don't log access to other assets
                        access_log off;
                    }
                }
            }
roboll / helmfile

expand errer (!) in a config block - can't process "://"? #973
