When running `gitconfig --local`, run it in subdirectories as well.

Summary:
The advantage of local is it doesn't pollute global state, but the
disadvantage is that the settings are not inherited by submodules.
(This is a misfeature, in my opinion.)  So whenever we set anything
--local, we need to manually do it in all submodules as well.

This isn't a perfect solution, since if new submodules are added later
they won't get the setting -- we'd have to hook into `git p` or
something for that -- but it's better than nothing!

In particular, it fixes (modulo the caveat above)
https://app.asana.com/0/31965416896056/172514774666235
and also
https://app.asana.com/0/31965416896056/51708574715815

Update submodules recursively, and do a better job parsing `status` output.

I wasn't doing recursive submodules before because I figured they
typically weren't *our* code so there was no point in using our
configs on them.  But there's no harm either, and they *can* be code
we care about, so let's just do it.

Just use no-arg `split` so we ignore leading spcae and runs of whitespace.

No-arg `split` is the best.

Test Plan:
I ran
   cd /tmp
   ~/khan/devtools/ka-clone/bin/ka-clone -p git@github.com:Khan/webapp
   cd webapp/intl/translations
   git config -l --local --includes | grep transport
and saw it say 'git-bigfile.transport=s3'.

On an old version of ka-clone, it did not say that.

(same)

(same)

Reviewers: mroth, benkraft

Reviewed By: benkraft

Differential Revision: https://phabricator.khanacademy.org/D34584

fix travis-ci by mocking git user

Tests assumed user already has a git environment user setup, but
travis-ci does not.  Mock the user setup in our fake $HOME so travis-ci
tests work again.

Auditors: csilvers

Test Plan:  deploy to alternate branch on github, watch travis-ci
results

fix broken test introduced with D20231

Summary:
the integration tests validate which hooks are installed, and was
failing because it was not updated to expect the new pre-rebase hook

Test Plan: - make tests

Reviewers: csilvers

Reviewed By: csilvers

Differential Revision: https://phabricator.khanacademy.org/D20238

fix: unlink symlinks before copying git hooks

there was an issue where if a git hook with the same name existed
already, but was a symlink, ka-clone would overrwrite the link
destination’s contents rather than replacing the symlink!  apparently
this is what python’s `shutil.copyfile` does by design.

as a fix, manually unlink any symlinks first to be extra safe, then use
`shutil.copy` instead.

#devenvfixup

Auditors: csilvers, ethan, mopewa

fix regression in --email option and zero args

option —email at CLI once again has highest precedence.  added an
integration test for this instance to make sure it stays fixed.

also fixed a regression that had broken printing help by default when
given zero args.

Review: D18650

Auditors: csilvers, alpert

read default email from gitconfig

Summary:
check standard git configuration hierarchy for presence of a
kaclone.email setting, and if so use that as the default instead of
inferring based on environment

Reviewers: csilvers

Reviewed By: csilvers

Subscribers: alpert

Projects: #devenvfixup

Differential Revision: https://phabricator.khanacademy.org/D18650