view mercurial/__init__.py @ 22178:70383c6961b4 stable

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.