Fix some mercurial edge cases
Summary:
- Old versions of Mercurial give different output for `hg log -- ''` and `hg log`. Just use `hg log`.
- Branch names with spaces can't be specified in `--rev`. I talked with hstuart in #mercurial and apparently am not crazy.
Test Plan:
- Viewed history of a repository.
- Viewed history of a file.
- Viewed branch `m m m m m 2:ffffffffffff (inactive)`
- Learned that you checkout this branch with `hg checkout ':m m m m m 2:ffffffffffff (inactive)'`
Reviewers: dschleimer, btrahan
Reviewed By: dschleimer
CC: aran
Maniphest Tasks: T1268
Differential Revision: https://secure.phabricator.com/D2950