branchcache: do not copy the `_dirty` flag
If the inherited branch cache is dirty, it will be written on disk, and the
super-set did not need to modify it, the on disk value for the subset will be
re-useable as is. So the super set does not needs to write the very same content
itself.
--- a/mercurial/branchmap.py Fri Mar 08 16:52:08 2024 +0100
+++ b/mercurial/branchmap.py Fri Mar 08 16:49:06 2024 +0100
@@ -569,9 +569,6 @@
closednodes=set(self._closednodes),
verify_node=self._verify_node,
)
- # we copy will likely schedule a write anyway, but that does not seems
- # to hurt to overschedule
- other._dirty = self._dirty
# also copy information about the current verification state
other._verifiedbranches = set(self._verifiedbranches)
return other