Make FakeRepos more reusable. Make it work with 'coverage'.

Make FakeRepos more reusable.
Make it work with 'coverage'.
Make FakeRepos initialization lazy. Only generate the repository when needed. It's in part intended for gclient_scm_tests.py but I left it out of this review.

To use:
  easy_install coverage
  ./tests/gclient_smoke.py -c
  coverage report

Current coverage with gclient_smoke:

Name                        Stmts   Exec  Cover
-----------------------------------------------
gclient                       557    416    74%
gclient_scm                   496    270    54%
gclient_utils                 195    117    60%
scm                           439    180    41%
(ignoring irrelevant files)

It's quite good in fact, 74% of gclient.py being executed with the smoke test.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=48501

[Nasser Grainawi, 2010-05-28 17:28:42]

'easy_install coverage' failed for me, but that's not your fault :)
lgtm