keyids in "apt-key del" should be case-insensitive

gnupg is case-insensitive about keyids, so back then apt-key called it
directly any keyid was accepted, but now that we work more with the
keyid ourself we regressed to require uppercase keyids by accident.

This is also inconsistent with other apt-key commands which still use
gnupg directly. A single case-insensitive grep and we are fine again.

Closes: 781696

cmdline/apt-key.in

@@ -180,7 +180,7 @@ update() {
 remove_key_from_keyring() {
     local GPG="$GPG_CMD --keyring $1"
     # check if the key is in this keyring: the key id is in the 5 column at the end
-    if ! $GPG --with-colons --list-keys 2>&1 | grep -q "^pub:[^:]*:[^:]*:[^:]*:[0-9A-F]*$2:"; then
+    if ! $GPG --with-colons --list-keys 2>&1 | grep -iq "^pub:[^:]*:[^:]*:[^:]*:[0-9A-F]*$2:"; then
 	return
     fi
     if [ ! -w "$1" ]; then

test/integration/test-apt-key

@@ -111,3 +111,9 @@ cleanplate
 cp -a keys/joesixpack.pub rootdir/etc/apt/trusted.gpg.d/joesixpack.gpg
 testsuccess --nomsg aptkey --fakeroot del 5A90D141DBAC8DAE
 testempty aptkey list
+
+msgtest 'Test key removal with' 'lowercase key ID' #keylength somewher between 8byte and short
+cleanplate
+cp -a keys/joesixpack.pub rootdir/etc/apt/trusted.gpg.d/joesixpack.gpg
+testsuccess --nomsg aptkey --fakeroot del d141dbac8dae
+testempty aptkey list