Inconsistent blank line from `update-repos -from_file=go.mod -prune -to_macro=...`

What version of gazelle are you using?

v0.23.0

What version of rules_go are you using?

v0.26.0

What version of Bazel are you using?

4.1.0

Does this issue reproduce with the latest releases of all the above?

Yes

What operating system and processor architecture are you using?

linux/amd64

What did you do?

This is a "minimal" example:

go.mod file:

module test

go 1.16

require github.com/getsentry/sentry-go v0.6.0

main.go file:

package main

import (
        "fmt"

        _ "github.com/getsentry/sentry-go"
)

func main() {
        fmt.Println("vim-go")
}

WORKSPACE file:

workspace(name = "test")

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

GO_VERSION = "1.16.6"

# For rules_go
RULES_GO_VERSION = "v0.26.0"

http_archive(
    name = "io_bazel_rules_go",
    sha256 = "7c10271940c6bce577d51a075ae77728964db285dac0a46614a7934dc34303e6",
    urls = [
        "https://mirror.bazel.build/github.com/bazelbuild/rules_go/releases/download/%s/rules_go-%s.tar.gz" % (RULES_GO_VERSION, RULES_GO_VERSION),
        "https://github.com/bazelbuild/rules_go/releases/download/%s/rules_go-%s.tar.gz" % (RULES_GO_VERSION, RULES_GO_VERSION),
    ],
)

# For gazelle
GAZELLE_VERSION = "v0.23.0"

http_archive(
    name = "bazel_gazelle",
    sha256 = "62ca106be173579c0a167deb23358fdfe71ffa1e4cfdddf5582af26520f1c66f",
    urls = [
        "https://storage.googleapis.com/bazel-mirror/github.com/bazelbuild/bazel-gazelle/releases/download/%s/bazel-gazelle-%s.tar.gz" % (GAZELLE_VERSION, GAZELLE_VERSION),
        "https://github.com/bazelbuild/bazel-gazelle/releases/download/%s/bazel-gazelle-%s.tar.gz" % (GAZELLE_VERSION, GAZELLE_VERSION),
    ],
)

load("@io_bazel_rules_go//go:deps.bzl", "go_register_toolchains", "go_rules_dependencies")
load("@bazel_gazelle//:deps.bzl", "gazelle_dependencies")

go_rules_dependencies()

go_register_toolchains(version = GO_VERSION)

gazelle_dependencies()

load("//:external.bzl", "go_dependencies")

# gazelle:repository_macro external.bzl%go_dependencies
go_dependencies()

BUILD.bazel file:

load("@bazel_gazelle//:def.bzl", "gazelle")

# gazelle:prefix test
gazelle(name = "gazelle")

initial external.bzl file:

def go_dependencies():
    pass

Run the following commands:

$ go mod tidy
$ bazel run //:gazelle -- update-repos -from_file=go.mod -prune -to_macro=external.bzl%go_dependencies

At this point, external.bzl file is auto populated like this, with no extra blank lines between go_repository:

$ head -n 51 external.bzl 
load("@bazel_gazelle//:deps.bzl", "go_repository")

def go_dependencies():
    go_repository(
        name = "com_github_ajg_form",
        importpath = "github.com/ajg/form",
        sum = "h1:t9c7v8JUKu/XxOGBU0yjNpaMloxGEJhUkqFRq0ibGeU=",
        version = "v1.5.1",
    )
    go_repository(
        name = "com_github_andreasbriese_bbloom",
        importpath = "github.com/AndreasBriese/bbloom",
        sum = "h1:HD8gA2tkByhMAwYaFAX9w2l7vxvBQ5NMoxDrkhqhtn4=",
        version = "v0.0.0-20190306092124-e2d15f34fcf9",
    )
    go_repository(
        name = "com_github_armon_consul_api",
        importpath = "github.com/armon/consul-api",
        sum = "h1:G1bPvciwNyF7IUmKXNt9Ak3m6u9DE1rF+RmtIkBpVdA=",
        version = "v0.0.0-20180202201655-eb2c6b5be1b6",
    )
    go_repository(
        name = "com_github_aymerick_raymond",
        importpath = "github.com/aymerick/raymond",
        sum = "h1:Ppm0npCCsmuR9oQaBtRuZcmILVE74aXE+AmrJj8L2ns=",
        version = "v2.0.3-0.20180322193309-b565731e1464+incompatible",
    )
    go_repository(
        name = "com_github_burntsushi_toml",
        importpath = "github.com/BurntSushi/toml",
        sum = "h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=",
        version = "v0.3.1",
    )
    go_repository(
        name = "com_github_cloudykit_fastprinter",
        importpath = "github.com/CloudyKit/fastprinter",
        sum = "h1:3SgJcK9l5uPdBC/X17wanyJAMxM33+4ZhEIV96MIH8U=",
        version = "v0.0.0-20170127035650-74b38d55f37a",
    )
    go_repository(
        name = "com_github_cloudykit_jet",
        importpath = "github.com/CloudyKit/jet",
        sum = "h1:rZgFj+Gtf3NMi/U5FvCvhzaxzW/TaPYgUYx3bAPz9DE=",
        version = "v2.1.3-0.20180809161101-62edd43e4f88+incompatible",
    )
    go_repository(
        name = "com_github_codegangsta_inject",
        importpath = "github.com/codegangsta/inject",
        sum = "h1:sDMmm+q/3+BukdIpxwO365v/Rbspp2Nt5XntgQRXq8Q=",
        version = "v0.0.0-20150114235600-33e0aa1cb7c0",
    )

Now upgrade the dependency to cause new dependencies being pulled in:

$ go get github.com/getsentry/sentry-go@v0.11.0
$ go mod tidy
$ bazel run //:gazelle -- update-repos -from_file=go.mod -prune -to_macro=external.bzl%go_dependencies

Some of the go_repository is removed from external.bzl, and some of the new go_repository is added, but after every block of added go_repository there's an extra blank line, for example:

$ head -n 58 external.bzl | tail -n 25
    go_repository(
        name = "com_github_cloudykit_fastprinter",
        importpath = "github.com/CloudyKit/fastprinter",
        sum = "h1:sR+/8Yb4slttB4vD+b9btVEnWgL3Q00OBTzVT8B9C0c=",
        version = "v0.0.0-20200109182630-33d98a066a53",
    )
    go_repository(
        name = "com_github_cloudykit_jet_v3",
        importpath = "github.com/CloudyKit/jet/v3",
        sum = "h1:1PwO5w5VCtlUUl+KTOBsTGZlhjWkcybsGaAau52tOy8=",
        version = "v3.0.0",
    )

    go_repository(
        name = "com_github_codegangsta_inject",
        importpath = "github.com/codegangsta/inject",
        sum = "h1:sDMmm+q/3+BukdIpxwO365v/Rbspp2Nt5XntgQRXq8Q=",
        version = "v0.0.0-20150114235600-33e0aa1cb7c0",
    )
    go_repository(
        name = "com_github_coreos_etcd",
        importpath = "github.com/coreos/etcd",
        sum = "h1:jFneRYjIvLMLhDLCzuTuU4rSJUjRplcJQ7pD7MnhC04=",
        version = "v3.3.10+incompatible",
    )

(com_github_cloudykit_jet_v3 is a new dependency added by the module upgrade, replacing the old com_github_cloudykit_jet)

What did you expect to see?

gazelle being consistent regarding the blank lines between go_repositorys.

bazelbuild / bazel-gazelle