exception-handling: better handling of remote exception and logging. - detect traceback sent form the remote sides - unified handling of exception handling in backends

hooks: added changes to propagate commit metadata on pre-push. This allows easier implementation of checking hooks such as branch protection.

release: merge back stable branch into default

Added tag v4.6.1 for changeset 8f7f4299bf34

release: Finish preparation for 4.6.1

release: updated pip2nix output for 4.6.1

release: Start preparation for 4.6.1

dependencies : bumped Mercurial version to 4.1.0. Now with new compression enabled.

mercurial: replace ancestor to pure python version for hg 4.1 compatability problems. this was moved now to debugcommands, but we don't need to run it via commands as the code is very simple.

dependencies: bumped pyramid to 1.7.4