xbps_repository_install_pkg: before adding pkg into the transaction,

check that it wasn't added before.

This change fixes and endless loop while doing the following:

$ xbps-bin install libXext libX11

where libX11 is a dependency of libXext and was already queued.

--HG--
extra : convert_revision : xtraeme%40gmail.com-20100114125713-o9vxzayz1tnhlt96

lib/repository_findpkg.c

@@ -342,6 +342,19 @@ xbps_repository_install_pkg(const char *pkg, bool by_pkgmatch)
 	if ((rv = create_transaction_dictionary()) != 0)
 		goto out;
 
+	/*
+	 * Check that this pkg hasn't been added previously into
+	 * the transaction.
+	 */
+	if (by_pkgmatch) {
+		if (xbps_find_pkg_in_dict_by_pkgmatch(trans_dict,
+		    "unsorted_deps", pkg))
+			return 0;
+	} else {
+		if (xbps_find_pkg_in_dict_by_name(trans_dict,
+		    "unsorted_deps", pkg))
+			return 0;
+	}
 	/*
 	 * Set repository in pkg dictionary.
 	 */