* epg.el (epg-process-sentinel): New function; set 'error if gpg
process exited abnormally, but we have not received an error
response from it.
+ (epg-sign-file): Signal an error only when a signature is not
+ created.
+ (epg-sign-string): Ditto.
+ (epg-encrypt-file): Signal an error if SIGN is specified and
+ signature is not created.
+ (epg-encrypt-string): Ditto.
2006-04-22 Daiki Ueno <ueno@unixuser.org>