Raise a setup warning for an unparseable VCS binary version
Summary:
Hit this locally, with an error like:
Version <empty string> is older than 1.9, the minimum supported version.
(Where <empty string> was just the empty string, not literally the text <empty string>.)
Be more careful about parsing versions, and parse the newer string.
Test Plan: Got "unknown version" with intentionally-broken test data, then clean readout.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Differential Revision: https://secure.phabricator.com/D11558