[PATCH 1/2] imap-hibernate: Fix out-of-bounds read when parsing DONE command tag

[PATCH 1/2] imap-hibernate: Fix out-of-bounds read when parsing DONE command tag

The tag-skipping loop was missing a size>0 guard, so a malformed
DONE command with no space/CR/tab terminator after the tag would
read one byte past the end of the buffer. Also add a \0 check to
stop on embedded null bytes, which are not valid tag characters.

Gbp-Pq: Name 0001-imap-hibernate-Fix-out-of-bounds-read-when-parsing-D.patch