# HG changeset patch
# User Durham Goode <durham@fb.com>
# Date 1399591986 25200
# Node ID 4aeb7a6029bafb4847bb27604a97d70ea1ee0fde
# Parent  4adc090fa2fb2d4e0094630a5440852d20cbd7ea
merge: prevent simplemerge from mutating label list

simplemerge was using list.pop() to remove items from the labels list. This
mutated the list and made it unusable by other calls (for instance, it might be
used in both the premerge and actual merge stages).

diff -r 4adc090fa2fb -r 4aeb7a6029ba mercurial/simplemerge.py
--- a/mercurial/simplemerge.py	Fri May 09 08:44:53 2014 +0900
+++ b/mercurial/simplemerge.py	Thu May 08 16:33:06 2014 -0700
@@ -416,11 +416,11 @@
     name_a = local
     name_b = other
     labels = opts.get('label', [])
-    if labels:
-        name_a = labels.pop(0)
-    if labels:
-        name_b = labels.pop(0)
-    if labels:
+    if len(labels) > 0:
+        name_a = labels[0]
+    if len(labels) > 1:
+        name_b = labels[1]
+    if len(labels) > 2:
         raise util.Abort(_("can only specify two labels."))
 
     try: