I managed to enter a newline in the Summary field, and the mail generated also had the newline: Subject: [Bug 140551] New: sshd fails to open ptys with RHEL4-re1122.nightly tree Content-type: text/plain; charset=utf-8 so half the headers were in the mail body - probably need to do some field sanitisation.
I fixed this by replacing newlines (and carriage returns) with spaces. This fix will be in version 2.18. Until 2.18 is in production, um, be careful. Or use the 2.18 beta (note: this fix hasn't been pushed out to the beta, yet, but it should be out soon)
Should be fixed now. Please reopen if not the case.