discovery: prevent crash on unknown remote heads with old repo (issue4337) When a remote is not capable of the `branchmap` wireproto command, we denote incoming heads with None. This leads to a crash in the code in charge of displaying the list of unknown remote heads. We now properly detect this case and display a shorter message in this case. The reason for this `set([None])` value is now documented.

obsstore.create: add a simple safeguard against cyclic markers We detect when there is a cycle in the marker itself (precursors being listed as successors).

debugobsolete: catch ValueError that may be raised by obsstore.create There are already a couple of errors that obsstore.create can raise and we are going to introduce a cycle check too.

check-code: extend try/except/finally check for multiple except clauses

repoview: fix try/except/finally for py2.4

merge with stable

test-run-tests: fix up slash/backslash on diff chunks for Windows

test-largefiles: add test for hg log --follow --patch with path This was the one case for test-largefiles that was not broken.

largefiles: don't override matchandpats for always matchers (issue4334) This makes hg log --follow --patch work, since in cmdutil._makelogrevset we use the non-follow matcher for hg log --follow --patch with no file arguments.

largefiles: in overridelog, use non-lf matcher for patch generation (issue4334) This has actually been broken since at least Mercurial 2.8 -- hg log --patch with largefiles only used to work when no largefiles existed. Rev 5809d62e7106 exposed this bug for all cases.

largefiles: drop setting lfstatus in overridelog (issue4334) lfstatus should only be True for operations where we want standins to be printed out. We explicitly do not want that for historical operations like log. Other historical operations like hg diff -r A -r B don't print out standins either. This is required to fix issue4334, but doesn't fix anything by itself. That's why there aren't any tests accompanying this patch.

cmdutil: add a hook for making custom non-follow log file matchers This will be used by largefiles (and basically only by largefiles) in an upcoming patch.

cmdutil: rename _makelogfilematcher to _makefollowlogfilematcher We're going to add a _makenofollowlogfilematcher in an upcoming patch.

merge with stable