fix mangling of "_" in mail Subject class name [SF#1413852]

Author: Richard Jones

CHANGES.txt

@@ -61,6 +61,7 @@ Fixed:
 - fix permission checks in cgi interface (sf bug 1289557)
 - fix permission check on RetireAction (sf bug 1407342)
 - timezone now applied to date for pretty-format (sf bug 1406861)
+- fix mangling of "_" in mail Subject class name (sf bug 1413852)
 
 
 2005-10-07 0.8.5

roundup/rfc2822.py

@@ -141,7 +141,7 @@ def encode_header(header, charset='utf-8'):
         if c == ' ':
             quoted += '_'
         # These characters can be included verbatim
-        elif hqre.match(c):
+        elif hqre.match(c) and c != '_':
             quoted += c
         # Otherwise, replace with hex value like =E2
         else: