[PATCH] crypto: return NULL cryptoctx if protocol string is empty.

[David Bremner]

Jameson Graef Rollins <jrollins at finestructure.net> writes:

> Badly formed messages that don't specify a protocol in
> signed/encrypted parts, end up with a protocol of NULL.  strcasecmp in
> notmuch_crypto_get_context then segfaults when trying to check it
> against known protocols.  If the protocol is NULL, just return an
> empty context immediately (with appropriate message.)

Pushed, thanks for the fix

d