brew update is broken due to donation note

[xu-cheng]

Please fill out the issue checklist below and provide all the requested information.

• [ ] ran a brew command and reproduced the problem with multiple formulae? If it's a problem with a single, official formula (not cask) please file this issue at Linuxbrew/homebrew-core: https://github.com/Linuxbrew/homebrew-core/issues/new/choose. If it's a brew cask problem please file this issue at https://github.com/Homebrew/homebrew-cask/issues/new/choose. If it's a tap (e.g. Homebrew/homebrew-php) problem please file this issue at the tap.
• [x] ran brew update and can still reproduce the problem?
• [x] ran brew doctor, fixed all issues and can still reproduce the problem?
• [x] ran brew config and brew doctor and included their output with your issue?

If the system git is too old, brew update will report the errors similar to the below.

 $ brew update
==> Linuxbrew is run entirely by unpaid volunteers. Please consider donating:                                                                     
  https://github.com/Linuxbrew/brew#donations                                                                                                     
error: unknown option `local'                                                                                                                     
usage: git config [options]                                                                                                                       

Config file location                                                                                                                              
    --global              use global config file                                                                                                  
    --system              use system config file                                                                                                  
    -f, --file <FILE>     use given config file                                                                                                   

Action                                                                                                                                            
    --get                 get value: name [value-regex]                                                                                           
    --get-all             get all values: key [value-regex]                                                                                       
    --get-regexp          get values for regexp: name-regex [value-regex]                                                                         
    --replace-all         replace all matching variables: name value [value_regex]                                                                
    --add                 adds a new variable: name value                                                                                         
    --unset               removes a variable: name [value-regex]                                                                                  
    --unset-all           removes all matches: name [value-regex]                                                                                 
    --rename-section      rename section: old-name new-name                                                                                       
    --remove-section      remove a section: name                                                                                                  
    -l, --list            list all                                                                                                                
    -e, --edit            opens an editor                                                                                                         
    --get-color <slot>    find the color configured: [default]                                                                                    
    --get-colorbool <slot>                                                                                                                        
                          find the color setting: [stdout-is-tty]                                                                                 

Type                                                                                                                                              
    --bool                value is "true" or "false"                                                                                              
    --int                 value is decimal number                                                                                                 
    --bool-or-int         value is --bool or --int                                                                                                
    --path                value is a path (file or directory name)                                                                                

Other                                                                                                                                             
    -z, --null            terminate values with NUL byte                                                                                          

Error: Failure while executing; `git config --local --replace-all homebrew.donationmessage true` exited with 129.           

This will only happen if the system git is too old to support --local flag. Noted that due to the Homebrew path filtering, brew update-report cannot find the brew git.

To workaround the issue, one can set HOMEBREW_NO_ENV_FILTERING=1. As for the fix, I would suggest:

• Turn safe_system to system, for the following codes: https://github.com/Linuxbrew/brew/blob/c918fcc1d954078f54a3475dcacc99377ec9b745/Library/Homebrew/cmd/update-report.rb#L49-L50 https://github.com/Linuxbrew/brew/blob/c918fcc1d954078f54a3475dcacc99377ec9b745/Library/Homebrew/cmd/update-report.rb#L62
• brew update-report or the whole homebrew code in general should use the git shim, which is specifically designed to search the proper git executable.

My brew config:

$ brew config
HOMEBREW_VERSION: 1.7.1-356-gc918fcc
ORIGIN: https://github.com/Linuxbrew/brew.git
HEAD: c918fcc1d954078f54a3475dcacc99377ec9b745
Last commit: 15 hours ago
Core tap ORIGIN: https://github.com/Linuxbrew/homebrew-core
Core tap HEAD: c82d598bc313e228592f283b88bf163635a9f215
Core tap last commit: 16 minutes ago
HOMEBREW_PREFIX: /home/comp/chengxu/usr
HOMEBREW_REPOSITORY: /home/comp/chengxu/usr
HOMEBREW_CELLAR: /home/comp/chengxu/usr/Cellar
HOMEBREW_CACHE: /tmp/chengxu/cache/homebrew
HOMEBREW_BOTTLE_DEFAULT_DOMAIN_LINUX: https://linuxbrew.bintray.com
HOMEBREW_BOTTLE_DEFAULT_DOMAIN_MACOS: https://homebrew.bintray.com
HOMEBREW_DEVELOPER: true
HOMEBREW_FORCE_VENDOR_RUBY: true
HOMEBREW_LOGS: /tmp/chengxu/cache/homebrew/logs
HOMEBREW_NO_ANALYTICS: true
HOMEBREW_NO_AUTO_UPDATE: true
HOMEBREW_SANDBOX: true
CPU: 24-core 64-bit westmere
Homebrew Ruby: 2.3.7 => /home/comp/chengxu/usr/Library/Homebrew/vendor/portable-ruby/2.3.7/bin/ruby
Clang: 6.0 build 601
Git: 2.18.0 => /home/comp/chengxu/usr/bin/git
Curl: 7.19.7 => /usr/bin/curl
Java: N/A
Kernel: Linux 2.6.32-754.el6.x86_64 x86_64 GNU/Linux
OS: CentOS release 6.10 (Final) (Final)
Host glibc: 2.14
/usr/bin/gcc: 4.4.7
glibc: 2.23
gcc: 5.5.0_4
xorg: 20170115

[sjackman]

Thanks for the bug report! Here's a quick fix PR https://github.com/Linuxbrew/brew/pull/821 which removes --local. The better solution is as you say is to use shims/scm/git.

[xu-cheng]

Thanks again for the fixing.

[sjackman]

No worries. Thanks for the bug report!