clfilter: add mutable filtering It filters all mutable changesets, leaving only public changeset unfiltered. This filtering set is expected to be much more stable that the previous one as public changeset are unlikely to disapear. The only official use of this filter is for branchcache.

run-tests.py: fix handling of symlink to the right python Before: a symlink for python in BINDIR was sometimes created, but it was never updated when a different Python was used and it was never removed. An invalid python could thus be left around and used when testing with --local. Now: the symlink is removed when wrong and created when necessary. The mechanism for finding the right name (python or python.exe) also had to be simplified and made more explicit.

log: use "hidden" filtering instead of manual check at display time When log is not given the --hidden option, hidden revision are not shown. We move the implementation from manual checking at display time to changelog filtering. This is the first official usage of the hidden filtering.

clfilter: introduces a hidden filter This filter exclude all hidden revision. We plan to use this filter to hide revision instead of manually checking contents of the hidden revisions set.