I recently upgraded my Bugzilla from 4.4.x to 5.0.1. I am now noticing that non-ASCII attachments -- even ones created years ago -- do not download correctly in any browser. For example, Microsoft Word attachments (MIME type "application/msword") are corrupted and don't display properly if at all. The same thing happens with binary file attachments (MIME type "application/octet-stream") and Excel files.
These are all relatively small files (under 200KB) that are stored in the MySQL attachment table. By retrieving one of the BLOBs directly, I verified that the content in the database is _not_ corrupted.
What seems to be happening is that all of these binary attachments are being converted to UTF-8 unconditionally. For example, a byte 0x82 in the original file is being converted to the 2-byte sequence 0xC2,0x82 in the downloaded version.
My server is Apache 2.2.22 running under Debian 7.9.
Any ideas how to fix this behavior?