I tried fixing the bug you reported, but couldn't simulate same situation as you described, even after importing the *.eml file into my GMail account.
Please look if the problem is fixed now, otherwise, I'd ask you to export a message to file using the methodExportForReportof the Message object and send it to me. The file contains the serialized message object, including the body parts, the content type, transfer encoding, the xmailer field and the subject.
I didn't update the binaries in the download section, please use the repo to get the latest version.