# HG changeset patch
# User Denis Laxalde <denis.laxalde@logilab.fr>
# Date 2017-01-16 16:08:25
# Node ID 21f1f97ab2123c27b2d09b9f9dc2e68af3fe10a9
# Parent  2912b06905dceb4fd668cd0a8d815ac9a001664b

context: add a followfirst flag to blockancestors

diff --git a/mercurial/context.py b/mercurial/context.py
--- a/mercurial/context.py
+++ b/mercurial/context.py
@@ -1166,7 +1166,7 @@ def _changesrange(fctx1, fctx2, linerang
     diffinrange = any(stype == '!' for _, stype in filteredblocks)
     return diffinrange, linerange1
 
-def blockancestors(fctx, fromline, toline):
+def blockancestors(fctx, fromline, toline, followfirst=False):
     """Yield ancestors of `fctx` with respect to the block of lines within
     `fromline`-`toline` range.
     """
@@ -1175,6 +1175,8 @@ def blockancestors(fctx, fromline, tolin
     while visit:
         c, linerange2 = visit.pop(max(visit))
         pl = c.parents()
+        if followfirst:
+            pl = pl[:1]
         if not pl:
             # The block originates from the initial revision.
             yield c