hgsubversion is effectively unmaintained right now. It doesn't work at

all with Python 3, and I'm even struggling to get it running on Python

2.7 with older Mercurial releases.
Assuming it continues in that state, I don't think many people are using

it, and we should probably consider removing it entirely. For now, this

change improves our test skipping machinery to prevent failures when we

can't successfully clone an SVN repository.

Made a temporary change to get things to proceed halfway in the way that

they are on some setups (past the basic check for hgsubversion but

failing when trying to clone). Saw that hgsubversion tests were

successfully skipped rather than causing errors.