Matt Robenolt 4c3ab41e90 Only update VCS when things have actually changed ... This saves a network hop when using git and passing an explicit sha as a ref by comparing the version that's already checked out. Yields a ~4x speedup on my local machine Before: ``` $ /usr/local/bin/pip --version pip 7.1.0 from /usr/local/lib/python2.7/site-packages (python 2.7) $ time /usr/local/bin/pip install --disable-pip-version-check -e git+https://github.com/getsentry/raven-python.git@56fc6f7beecf445843d0ec7052bb8c6f0ea80a2e#egg=raven_dev Obtaining raven-dev from git+https://github.com/getsentry/raven-python.git@56fc6f7beecf445843d0ec7052bb8c6f0ea80a2e#egg=raven_dev Updating ./src/raven-dev clone (to 56fc6f7beecf445843d0ec7052bb8c6f0ea80a2e) Could not find a tag or branch '56fc6f7beecf445843d0ec7052bb8c6f0ea80a2e', assuming commit. Installing collected packages: raven-dev Running setup.py develop for raven-dev Successfully installed raven-dev /usr/local/bin/pip install --disable-pip-version-check -e 0.84s user 0.48s system 39% cpu 3.300 total ``` After: ``` $ /Users/matt/.virtualenvs/pip/bin/pip --version pip 7.2.0.dev0 from /Users/matt/code/pip (python 2.7) $ time /Users/matt/.virtualenvs/pip/bin/pip install --disable-pip-version-check -e git+https://github.com/getsentry/raven-python.git@56fc6f7beecf445843d0ec7052bb8c6f0ea80a2e#egg=raven_dev Obtaining raven-dev from git+https://github.com/getsentry/raven-python.git@56fc6f7beecf445843d0ec7052bb8c6f0ea80a2e#egg=raven_dev checking version Skipping because already up-to-date. Installing collected packages: raven-dev Running setup.py develop for raven-dev Successfully installed raven-dev /Users/matt/.virtualenvs/pip/bin/pip install --disable-pip-version-check -e 0.59s user 0.22s system 98% cpu 0.824 total ```		2015-09-01 13:23:18 -07:00
..
__init__.py	Only update VCS when things have actually changed	2015-09-01 13:23:18 -07:00
bazaar.py	Only update VCS when things have actually changed	2015-09-01 13:23:18 -07:00
git.py	Only update VCS when things have actually changed	2015-09-01 13:23:18 -07:00
mercurial.py	Only update VCS when things have actually changed	2015-09-01 13:23:18 -07:00
subversion.py	Only update VCS when things have actually changed	2015-09-01 13:23:18 -07:00