comments: describe ancestor consistently - avoid 'least common ancestor'

"best" is as defined by mercurial.ancestor.ancestors: furthest from a root (as
measured by longest path).

mercurial/context.py

@@ -542,9 +542,11 b' class changectx(basectx):'
                        changectx=self, filelog=filelog)
 
     def ancestor(self, c2, warn=False):
-        """
-        return the "best" ancestor context of self and c2
-        """
+        """return the "best" ancestor context of self and c2
+
+        If there are multiple candidates, it will show a message and check
+        merge.preferancestor configuration before falling back to the
+        revlog ancestor."""
         # deal with workingctxs
         n2 = c2._node
         if n2 is None:
@@ -1146,7 +1148,7 b' class committablectx(basectx):'
             return ''
 
     def ancestor(self, c2):
-        """return the ancestor context of self and c2"""
+        """return the "best" ancestor context of self and c2"""
         return self._parents[0].ancestor(c2) # punt on two parents for now
 
     def walk(self, match):

mercurial/revlog.py

@@ -753,7 +753,7 b' class revlog(object):'
         return a in self.commonancestorsheads(a, b)
 
     def ancestor(self, a, b):
-        """calculate the least common ancestor of nodes a and b"""
+        """calculate the "best" common ancestor of nodes a and b"""
 
         a, b = self.rev(a), self.rev(b)
         try:

tests/test-merge-default.t

@@ -97,8 +97,7 b' Should fail because merge with other bra'
 
 
 Test for issue2043: ensure that 'merge -P' shows ancestors of 6 that
-are not ancestors of 7, regardless of where their least common
-ancestor is.
+are not ancestors of 7, regardless of where their common ancestors are.
 
 Merge preview not affected by common ancestor: