repo-add: implicitly sign when verifying

Currently it is possible to verify a database signature, without signing
the database. This causes the database to be altered, but the (then
invalid) signature to be preserved.

Fix this by implicitly signing when verifying.

Signed-off-by: Christian Hesse <mail@eworm.de>

doc/repo-add.8.asciidoc

@@ -54,7 +54,7 @@ Common Options
 *-v, \--verify*::
 	Verify the PGP signature of the database before updating the database.
 	If the signature is invalid, an error is produced and the update does not
-	proceed.
+	proceed. This implicitly enabled signing.
 
 *\--nocolor*::
 	Remove color from 'repo-add' and 'repo-remove' output.

scripts/repo-add.sh.in

@@ -631,6 +631,7 @@ while true; do
 			GPGKEY=$1
 			;;
 		-v|--verify)
+			SIGN=1
 			VERIFY=1
 			;;
 		-p|--prevent-downgrade)