Mailing sent to a group that is not a mailing list ignores From Address for replies, uses default From Address

When a mailing is sent to a Group that is not a mailing list (see this issue: https://issues.civicrm.org/jira/browse/CRM-17320) any replies to the sent email will ignore the selected From Address and send/reply to the default From Address instead.

To reproduce:

1. I created a new From email address here: http://d46.demo.civicrm.org/civicrm/admin/options/from_email_address?action=update&id=831&reset=1
2. I followed these steps outlined in ticket CRM-17320
   1. I set up a Mailing List group called "Test Group 1" on the demo site here: http://d46.demo.civicrm.org/civicrm/group/search?force=1&context=smog&gid=8
   2. I created and sent a mailing to this group here: http://d46.demo.civicrm.org/civicrm/mailing/report?mid=17&reset=1
   3. Unchecked the "Mailing List" checkbox on the "Test Group 1" group
      Went to Scheduled and Sent Mailings, and clicked the Re-use link to the right of the mailing I'd sent earlier
   4. There are no recipients displayed in the Recipients field, yet the recipient count to the right of that field shows that ~1 contact will receive the mailing.
3. At this point I selected my new From email address, changed the Mailing Name to Test Email 2 and sent it.
4. After processing the mailing I looked at the report and as you can see in the attached screenshot the "From" email is what i selected, but the reply to email address is the default.
5. The demo site doesn't seem to be configured to actually send emails, but testing on our live server shows that when the email is received the from address is correct, but replies to the sent email will go back to the default from email address.