pycompat: add util.urlerr util.urlreq classes for py3 compat python3 url.request and url.error are mapped as util.urlreq/util.urlerr python2 equivalents from urllib/urllib2 are mapped according to the py3 hierarchy

test-progress: disable mocking-time tests on chg It's hard to make these tests compatible with chg because a mocked time.time() is recorded and accessed by progbar at random timing. I don't think it's worth fixing this test as it is considered a unit test of time estimates, so just ignores on chg.

hghave: add "chg" flag to skip tests that can't be compatible with chg Several tests fail with chg for several reasons such as loaded chgserver extension, running uisetup() per server instead of per runcommand, etc. Since these tests can't/shouldn't be changed to be chg friendly, we need a flag to skip them. This patch explicitly drops CHGHG environment if chg isn't involved. This way, hghave can just check if CHGHG exists.