revset: special case commonancestors(none()) to be empty set This matches the behavior of ancestor(none()). From an implementation perspective, ancestor() and commonancestors() are intersection, and ancestors() is union, so it would make some sense that commonancestors(none()) returned all revisions. However, ancestor(none()) isn't implemented as such, which breaks ancestor(x) == max(commonancestors(x)). From a user perspective, ancestors of nothing is nothing whichever type of operation the ancestor predicate does.

revset: clarify heads() order doesn't matter while computing common ancestors Follows up 5460926352ee and 52f19a840543.

hghave: require clang-format >= 6 due to output change

cext: reformat with clang-format 6.0 It appears some changes in clang-format affect our code. I didn't dig into that deeper since the new output looks better.

py3: use bytes() to byte-stringify Abort message in handleremotechangegroup()

py3: don't str() to byte-stringify object in test-bundle2-remote-changegroup.t

py3: byte-stringify literals in extension in test-bundle2-remote-changegroup.t # skip-blame just some b''

py3: open file in binary mode in test-bundle2-remote-changegroup.t

statprof: small if cleanup Explicitly testing for None to avoid comparison bugs.

store: assert the fncache have been loaded if dirty This should catch fncache corruption as the one that existed in `perffncachewrite`.