[PATCH 1 of 2] pullbundle2: extract addchangegroup result comining into its own function

[Eric Sumner]

# HG changeset patch
# User Eric Sumner <ericsumner at fb.com>
# Date 1421441625 28800
#      Fri Jan 16 12:53:45 2015 -0800
# Node ID 27a61fc3498b0bae606cbc92801a9103015090d4
# Parent  e07587a186a859fdb065b9475afd0470e2ae4508
pullbundle2: extract addchangegroup result comining into its own function

This will also be used for 'hg unbundle'

diff --git a/mercurial/changegroup.py b/mercurial/changegroup.py
--- a/mercurial/changegroup.py
+++ b/mercurial/changegroup.py
@@ -42,6 +42,24 @@
     """return a changegroup chunk header (string) for a zero-length chunk"""
     return struct.pack(">l", 0)
 
+def combineresults(results):
+    """logic to combine 0 or more addchangegroup results into one"""
+    changedheads = 0
+    for ret in results:
+        # If any changegroup result is 0, return 0
+        if ret == 0:
+            return 0
+        if ret < -1:
+            changedheads += ret + 1
+        elif ret > 1:
+            changedheads += ret - 1
+    if changedheads > 0:
+        return 1 + changedheads
+    elif changedheads < 0:
+        return -1 + changedheads
+    else:
+        return 0
+
 class nocompress(object):
     def compress(self, x):
         return x
diff --git a/mercurial/exchange.py b/mercurial/exchange.py
--- a/mercurial/exchange.py
+++ b/mercurial/exchange.py
@@ -992,6 +992,8 @@
         raise util.Abort('missing support for %s' % exc)
 
     if pullop.fetch:
+        results = [cg['return'] for cg in op.records['changegroup']]
+        pullop.cgresult = changegroup.combineresults(results)
         changedheads = 0
         pullop.cgresult = 1
         for cg in op.records['changegroup']: