test-run-tests: add a test for detection of failure to start a server This also highlights a bug: right now we print "2 failed" but we only ran one test.

run-tests: more accurate/helpful message than "diff generation failed" Diff generation didn't really fail, it recognized that an hg serve server has failed to start, and thus skipped the diff generation intentionally. The most common reason for a server to fail to start is that the port was already in use, so output HGPORT as well, to help finding it (since pgrep -f 'hg serve' is not sufficient, if the command line is something like 'hg -R main serve')

run-tests: handle --jobs and --first gracefully Without this change, --first causes currently-running tests to explode in violent and surprising ways when their temporary directory gets cleaned up. Now we just suppress failure messages from non-first failures when running in --first mode.

config: use the same hgrc for a cloned repo as for an uninitted repo This just copies the same local sample hgrc, except it sets the default path to the repo it was cloned from. This is cut-and-paste from the local sample hgrc, but I think it's acceptable, since the two pieces of code are right next to each other and they're small. There is danger of them going out of synch, but it would complicate the code too much to get rid of this C&P. I also add ui as an import to hg.py, but with demandimport, this should not be a noticeable performance hit.