[PATCH 7 of 8] hidden: make _revealancestors() reveal ancestors exclusively

[Martin von Zweigbergk]

# HG changeset patch
# User Martin von Zweigbergk <martinvonz at google.com>
# Date 1495951510 25200
#      Sat May 27 23:05:10 2017 -0700
# Node ID 55c2e0b946ab4b00c8cb481b92881d4c9ccb0707
# Parent  f8b3d943ff21a2b906f2806476a637aac93763c4
hidden: make _revealancestors() reveal ancestors exclusively

I think this seems more expected.

diff --git a/mercurial/repoview.py b/mercurial/repoview.py
--- a/mercurial/repoview.py
+++ b/mercurial/repoview.py
@@ -52,11 +52,10 @@
     - pfunc(r): a funtion returning parent of 'r',
     - revs: iterable of revnum,
 
-    (Ancestors are revealed inclusively, i.e. the elements in 'revs' are
-    also revealed)
+    (Ancestors are revealed exclusively, i.e. the elements in 'revs' are
+    *not* revealed)
     """
     stack = list(revs)
-    hidden -= set(stack)
     while stack:
         for p in pfunc(stack.pop()):
             if p != nullrev and p in hidden:
@@ -78,8 +77,7 @@
         visible = set(mutable - hidden)
         visible |= (hidden & anchorrevs(repo))
         if visible:
-            # don't modify possibly cached result of hideablerevs()
-            hidden = hidden.copy()
+            hidden = hidden - visible
             _revealancestors(hidden, pfunc, visible)
     return frozenset(hidden)