Concatenate raw diffs as bytes.
Concatenate raw diffs as bytes.

The raw diff method was concatenating all the individual file diffs using '',
but those file diffs may be undecoded string data that doesn't parse as
unicode. This changes it to use b''.

Trivial change.

custode/reviewboard,chipx86/reviewboard,chipx86/reviewboard,chipx86/reviewboard,1tush/reviewboard,KnowNo/reviewboard,beol/reviewboard,davidt/reviewboard,reviewboard/reviewboard,beol/reviewboard,bkochendorfer/reviewboard,davidt/reviewboard,KnowNo/reviewboard,custode/reviewboard,bkochendorfer/reviewboard,chipx86/reviewboard,brennie/reviewboard,1tush/reviewboard,sgallagher/reviewboard,reviewboard/reviewboard,KnowNo/reviewboard,brennie/reviewboard,sgallagher/reviewboard,1tush/reviewboard,davidt/reviewboard,KnowNo/reviewboard,1tush/reviewboard,beol/reviewboard,beol/reviewboard,custode/reviewboard,reviewboard/reviewboard,1tush/reviewboard,custode/reviewboard,brennie/reviewboard,bkochendorfer/reviewboard,1tush/reviewboard,sgallagher/reviewboard,1tush/reviewboard,reviewboard/reviewboard,brennie/reviewboard,davidt/reviewboard,1tush/reviewboard,sgallagher/reviewboard,bkochendorfer/reviewboard,1tush/reviewboard