Add a plugin to prefix an issue number with a user-defined string.

plugins/issue_prefix/__init__.py

@@ -0,0 +1,15 @@
+# encoding=UTF-8
+"""__init__.py"""
+import re
+
+def build_filter(args):
+    return Filter(args)
+
+class Filter:
+    def __init__(self, args):
+        self.prefix = args
+
+    def commit_message_filter(self, commit_data):
+        for match in re.findall('#[1-9][0-9]+', commit_data['desc']):
+            commit_data['desc'] = commit_data['desc'].replace(
+                match, '#%s%s' % (self.prefix, match[1:]))