Strip comments from trailers for stg mail --auto

Commits in the Linux kernel repo include 'Cc: ' trailers that contain
comments starting with '#'. When these commented trailers are incorporated
directly into email headers, the email will be rejected due to the invalid
syntax of the comments in the context of an email address.

Repairs #91

Author: jpgrayson

stgit/commands/mail.py

@@ -510,13 +510,19 @@ def __get_signers_list(msg):
         'suggested-by',
         'reported-and-tested-by',
     )
-    regex = r'^(%s):\s+(.+)$' % tags
+
+    # N.B. This regex treats '#' as the start of a comment and thus discards everything
+    # after the '#'. This does not allow for valid email addresses that contain '#' in
+    # the local-part (i.e. the part before the '@') as is allowed by RFC2822. Such email
+    # addresses containing '#' in their local-part are thus not supported by this
+    # function.
+    regex = r'^(%s):\s+([^#]+).*$' % tags
 
     r = re.compile(regex, re.I)
     for line in msg.split('\n'):
         m = r.match(line)
         if m:
-            addr_list.append(m.expand(r'\g<2>'))
+            addr_list.append(m.group(2))
 
     return addr_list
 

t/t1900-mail.sh

@@ -75,6 +75,42 @@ test_expect_success 'Check the e-mail address duplicates' '
     test "$(cat mbox | grep -e "^Bcc:")" = "Bcc: d@d"
 '
 
+test_expect_success 'Check --auto with commented Cc: realname and addr' '
+    stg edit -m "Patch 5
+
+Cc: Some Body <[email protected]> # v3.2.1
+" &&
+    stg mail --auto $(stg top) -m > mbox &&
+    test "$(cat mbox | grep -e "^Cc:" | head -n 1)" = "Cc: Some Body <[email protected]>"
+'
+
+test_expect_success 'Check --auto with commented Cc: addr only' '
+    stg edit -m "Patch 5
+
+Cc: [email protected] # v3.2.1
+" &&
+    stg mail --auto $(stg top) -m > mbox &&
+    test "$(cat mbox | grep -e "^Cc:" | head -n 1)" = "Cc: [email protected]"
+'
+
+test_expect_success 'Check --auto with no-space commented Cc: realname and addr' '
+    stg edit -m "Patch 5
+
+Cc: Some Body <[email protected]>#v3.2.1
+" &&
+    stg mail --auto $(stg top) -m > mbox &&
+    test "$(cat mbox | grep -e "^Cc:" | head -n 1)" = "Cc: Some Body <[email protected]>"
+'
+
+test_expect_success 'Check --auto with no-space commented Cc: addr only' '
+    stg edit -m "Patch 5
+
+Cc: [email protected]#v3.2.1
+" &&
+    stg mail --auto $(stg top) -m > mbox &&
+    test "$(cat mbox | grep -e "^Cc:" | head -n 1)" = "Cc: [email protected]"
+'
+
 test_expect_success 'Test no patches' '
     command_error stg mail
 '