subrepo: use environment variable instead of git commit's --date Older git versions do not have a --date flag.

subrepo: parse git status's human-readable output Older git versions do not have a machine-readable output, but the default format has not changed over time.

subrepo: use subprocess's cwd instead of git's --work-tree Some older git commands (e.g. git merge) do not properly recognize the --work-tree argument, so abstract that away from git.

test-subrepo-git.t: make gitroot pushable earlier Older git versions get confused when the git repo becomes bare.

test-subrepo-git.t: silence git output Older git versions have different ideas of what output is considered quiet, so the tests can be more version-blind.

bdiff: Fix bogus NULL return

bdiff: dynamically allocate hunks Make the hunk list a singly-linked list rather than a large array.

merge with stable

subrepo: lazily update git's local tracking branches This continues the strategy of separation between hg pull and hg update in git subrepos by only dealing with git's branches on an update. This behavior tries to cover the bare essentials of the semantics of git pull in the subrepo when the parent repo does hg pull and hg update.

subrepo: return both mapping directions from gitbranchmap