add and use 'apt-key verify' which prefers gpgv over gpg

gnupg/gnupg2 can do verify just fine of course, so we don't need to use
gpgv here, but it is what we always used in the past, so there might be
scripts expecting a certain output and more importantly the output of
apt-cdrom contains messages from gpg and even with all the settings we
activate to prevent it, it still shows (in some versions) a quiet scary:
"gpg: WARNING: Using untrusted key!" message. Keeping the use of gpgv is
the simplest way to prevent it.

We are increasing also the "Breaks: apt" version from libapt as it
requires a newer apt-key than might be installed in partial upgrades.

apt-pkg/contrib/gpgv.cc

@@ -55,7 +55,7 @@ void ExecGPGV(std::string const &File, std::string const &FileGPG,
    Args.push_back(aptkey.c_str());
    Args.push_back("--quiet");
    Args.push_back("--readonly");
-   Args.push_back("adv");
+   Args.push_back("verify");
 
    char statusfdstr[10];
    if (statusfd != -1)
@@ -77,7 +77,6 @@ void ExecGPGV(std::string const &File, std::string const &FileGPG,
 	 Args.push_back(Opts->Value.c_str());
       }
    }
-   Args.push_back("--verify");
 
    enum  { DETACHED, CLEARSIGNED } releaseSignature = (FileGPG != File) ? DETACHED : CLEARSIGNED;
    std::vector<std::string> dataHeader;

cmdline/apt-key.in

@@ -450,6 +450,14 @@ case "$command" in
 	$GPG "$@"
 	merge_back_changes
 	;;
+    verify)
+	setup_merged_keyring
+	if which gpgv >/dev/null 2>&1; then
+	    gpgv --homedir "${GPGHOMEDIR}" --keyring "${GPGHOMEDIR}/pubring.gpg" --ignore-time-conflict "$@"
+	else
+	    $GPG --verify "$@"
+	fi
+	;;
     help)
         usage
         ;;

debian/control

@@ -43,7 +43,7 @@ Architecture: any
 Multi-Arch: same
 Pre-Depends: ${misc:Pre-Depends}
 Depends: ${shlibs:Depends}, ${misc:Depends}
-Breaks: apt (<< 0.9.4~), libapt-inst1.5 (<< 0.9.9~)
+Breaks: apt (<< 1.0.2~), libapt-inst1.5 (<< 0.9.9~)
 Section: libs
 Description: package management runtime library
  This library provides the common functionality for searching and