Handle a missing "cvs" binary better.

Review Request #886 — Created June 7, 2009 and submitted — Latest diff uploaded


Review Board SVN (deprecated)


Handle a missing "cvs" binary better.

In our dependency checks, SCMTool and unit tests, we didn't handle a missing
"cvs" binary in the same way we do for many of our other dependencies. I noticed
this because Ubuntu doesn't install CVS by default anymore (hooray!). This
change fixes up all the places so that we don't throw errors.