apt-key: add \n to dpkg-query --show --showformat

Guarding against 'broken' greps not dealing with non-text inputs
"just in case" by making the input text with a proper newline.

[commit message by David Kalnischkies]

Reported-On: IRC
Git-Dch: Ignore

cmdline/apt-key.in

@@ -498,7 +498,7 @@ prepare_gpg_home() {
     # well as the script hopefully uses apt-key optionally then like e.g.
     # debian-archive-keyring for (upgrade) cleanup did
     if [ -n "$DPKG_MAINTSCRIPT_PACKAGE" ]; then
-	if ! dpkg-query --show --showformat '${Pre-Depends}${Depends}${Recommends}' "$DPKG_MAINTSCRIPT_PACKAGE" 2>/dev/null | grep -q gnupg; then
+	if ! dpkg-query --show --showformat '${Pre-Depends}${Depends}${Recommends}\n' "$DPKG_MAINTSCRIPT_PACKAGE" 2>/dev/null | grep -q gnupg; then
 	    cat >&2 <<EOF
 Warning: The $DPKG_MAINTSCRIPT_NAME maintainerscript of the package $DPKG_MAINTSCRIPT_PACKAGE
 Warning: seems to use apt-key (provided by apt) without depending on gnupg or gnupg2.