fix(git-spawn): Add custom Batch wrapper when using plink.exe (#4729)

[neonowy]

Summary

Fixes #4729.

The main issue is that we use GIT_SSH_COMMAND instead of GIT_SSH, as we have to pass -batch argument in order to use ssh/plink in the non-interactive mode. Unfortunately, Git converts -p to -P for plink.exe only when using GIT_SSH.

The only way I could find to get out of this tricky issue is to create a wrapper script responsible for the -p/-P conversion and use it when plink.exe is provided via GIT_SSH.

Similar issue was also described here: https://jira.atlassian.com/browse/SRCTREEWIN-5600?page=com.atlassian.jira.plugin.system.issuetabpanels%3Aall-tabpanel

I'm not quite sure if the bin/ directory is the best place for the wrapper script yarn-plink.cmd, would scripts/ be a better choice?

Test plan

Before:

After:

I've also updated the test suite for git-spawn.js accordingly, but couldn't figure out how to test the yarn-plink.cmd wrapper script.

[buildsize]

This change will increase the build size from 9.94 MB to 9.94 MB, an increase of 1.71 KB (0%)

File name	Previous Size	New Size	Change
yarn-[version].noarch.rpm	859.9 KB	860.36 KB	467 bytes (0%)
yarn-[version].js	3.78 MB	3.78 MB	264 bytes (0%)
yarn-legacy-[version].js	3.83 MB	3.83 MB	290 bytes (0%)
yarn-v[version].tar.gz	865.48 KB	865.79 KB	316 bytes (0%)
yarn_[version]all.deb	654.43 KB	654.84 KB	418 bytes (0%)

[buildsize]

This change will increase the build size from 9.94 MB to 9.94 MB, an increase of 1.71 KB (0%)

File name	Previous Size	New Size	Change
yarn-[version].noarch.rpm	859.9 KB	860.36 KB	467 bytes (0%)
yarn-[version].js	3.78 MB	3.78 MB	264 bytes (0%)
yarn-legacy-[version].js	3.83 MB	3.83 MB	290 bytes (0%)
yarn-v[version].tar.gz	865.48 KB	865.79 KB	316 bytes (0%)
yarn_[version]all.deb	654.43 KB	654.84 KB	418 bytes (0%)

[arcanis]

Unfortunately that won't work with the single-file releases, so I don't think we can merge it :(

[neonowy]

@arcanis Oh, I didn't think of that. 😢

But actually, I think I found another (even better) way of doing this! Apparently GIT_SSH_VARIANT variable was added to Git, so we can just set it properly and it should work.

[BYK]

@neonowy are you sure it is not this line forcing everything to be lower case:

yarn/src/util/git/git-spawn.js

Line 17 in 6b185c2

const sshExecutable = path.basename(sshCommand.toLowerCase(), '.exe');

[neonowy]

@BYK I've tested it and it doesn't make any difference. If I understand this code right, we're using sshCommand directly when setting env.GIT_SSH_COMMAND and sshExecutable is only used as a normalized key for BATCH_MODE_ARGS here.

[neonowy]

Closing in favor of #4806.