--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/components/mercurial/patches/issue4646.patch	Wed May 06 10:05:59 2015 -0700
@@ -0,0 +1,45 @@
+# HG changeset patch
+# User Gregory Szorc <[email protected]>
+# Date 1430931130 25200
+#      Wed May 06 09:52:10 2015 -0700
+# Branch stable
+# Node ID 44b054c3a46eac63d5fed06ffb8fffc38d5668f6
+# Parent  41cd8171e58f991373dcd0b4897dc1e5978d42dd
+extensions: clear aftercallbacks after execution (issue4646)
+
+It was reported that enabling pager without color could cause a hang.
+Inserting print statements revealed that the callbacks in
+extensions._aftercallbacks were being invoked twice.
+
+extensions.loadall can be called multiple times. If entries in
+extensions._aftercallbacks linger between calls, this could result
+in double execution of the callbacks. This can lead to unwanted
+behavior.
+
+The reproduce steps in the bug seem to only occur when the output of
+a command is less than the size of the current screen. This is not
+something that can easily be tested. I verified the test case works
+with this patch and that pager and color interaction continues to
+work. Since we have no existing automated tests for pager, this sadly
+appears to be the best testing I can do.
+
+diff --git a/mercurial/extensions.py b/mercurial/extensions.py
+--- a/mercurial/extensions.py
++++ b/mercurial/extensions.py
+@@ -133,8 +133,12 @@ def loadall(ui):
+ 
+         for fn in _aftercallbacks[shortname]:
+             fn(loaded=False)
+ 
++    # loadall() is called multiple times and lingering _aftercallbacks
++    # entries could result in double execution. See issue4646.
++    _aftercallbacks.clear()
++
+ def afterloaded(extension, callback):
+     '''Run the specified function after a named extension is loaded.
+ 
+     If the named extension is already loaded, the callback will be called
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