git_lock_handler hardcodes git config info

[ywei2017]

The following lines hardcodes, and over-rides the "git_config" settings.

https://github.com/concourse/pool-resource/blob/6de7c7ad1b3439a72864153c6a86e3e026fb98dd/out/git_lock_handler.go#L208

Suggested Behavior:

• Only configure the hard-coded settings as default, if user.name and user.email are not present in git_config.

Thanks Yansheng

[ywei2017]

Since I no longer work on the project, closing the issue.