debian: update copyright years

debian: update mailing list address

bundle2: implement a basic __repr__ for bundle2 part We display basic data as the part id and part type. This make debugging bundle2 related code friendlier.

bundle2: drop an outdated comment The function is no longer in "early" stage and have been used in production for years. We can probably drop that part of the docstring...

unbundle: swap conditional branches for clarity This is a small style update for clarity. The previous situation was: if foo: 50 lines else: 2 lines In such case I tend to invert these to get the simpler branch out of the way earlier: if not foo: 2 lines else: 50 lines This makes the conditional and various alternatives fit on the same screen, simpler to read overall.

unbundle: add a small comment to tag the bundle1 case as such This makes the code clearer to understand for someone new to it (or rusted)

unbundle: add a small comment to clarify the 'check_heads' call Bundle2 has its own mechanisms to check for heads (and other) changes, so push using bundle2 is relying on the "check:heads" bundle part of unbundle and the 'check_heads' call is not checking anything. We add a small comment to make this clearer.

pager: don't terminate with extreme prejudice on SIGPIPE (BC) The default SIGPIPE handler causes Mercurial to exit immediately, without running any Python cleanup code (except and finally blocks, atexit handlers etc). This creates problems if you want to do something at exit. If we need a different exit code for broken pipe from pager, then we should code that ourselves in Python; this appears to have been cargo-culted from the fork implementation of pager that's no longer used, where it was needed to stop Broken Pipe errors appearing on the user's terminal.