changectx: ancestor should only prefer merge.preferancestor if it is a revision The value '*' currently designates that bid merge should be used. The best way to test bid merge is to set preferancestor=* in the configuration file ... but then it would abort with unknown revision '*' when other code paths ended up in changectx.ancestor . Instead, just skip and ignore the value '*' when looking for a preferred ancestor.

merge: show the scary multiple ancestor hint for merges only, not for updates Updates with uncommited changes will always only have one ancestor - the parent revision. Updates between existing revision should (and will) always give the same result no matter which ancestor is used. The warning is thus only relevant when doing a "real" merge.

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