exchange: switch to usual way of testing for bundle2-ness We used safehasattr() in one place, but we use isinstance() for this everywhere else, so switch to the latter.

setup: update a comment that blamed py26 for a Windows workaround

i18n: drop a py25 conditional I'm not sure how to test this one. `make update-pot` spews all kinds of warnings, though it did before this change too.

perf: ensure HGRCPATH is exported on Windows After dropping the garbage collector hack, `hg perfstartup` started yelling about not being able to import the evolve extension, which I have in my user config. Launching `env` shows that an empty HGRCPATH isn't exported to the environment. Since `env` doesn't quote, I have no idea if the variable is trimmed, but Mercurial doesn't complain when processing it.

test-status: glob fixes for Windows

plan9: drop py26 hacks

revset: fix negative ancestor spec to not return changectx objects The order was unstable because of this.

obsolete: use ProgrammingError over assert for volatile set registration We have ProgrammingError now.

strip: remove a redundant setting of hookargs bundle2.applybundle() will set both 'source' and 'url'.

unbundle: move streamclone error case away from bundle[12] cases The bundle1 and bundle2 cases are more similar, and having the streamclone case in between is distracting.