use rb_uri_is_descendant in a few places

This is better than the string prefix checks we had before as it ensures
that the end of the ancestor URI is also the end of a path component of
the descendant.

plugins/generic-player/rb-generic-player-source.c

@@ -683,7 +683,7 @@ default_uri_from_playlist_uri (RBGenericPlayerSource *source, const char *uri)
 	char *full_uri;
 
 	mount_uri = rb_generic_player_source_get_mount_path (source);
-	if (g_str_has_prefix (uri, mount_uri)) {
+	if (rb_uri_is_descendant (uri, mount_uri)) {
 		return g_strdup (uri);
 	}
 
@@ -704,7 +704,7 @@ default_uri_to_playlist_uri (RBGenericPlayerSource *source, const char *uri, Tot
 	case TOTEM_PL_PARSER_IRIVER_PLA:
 		/* we need absolute paths within the device filesystem for this format */
 		mount_uri = rb_generic_player_source_get_mount_path (source);
-		if (g_str_has_prefix (uri, mount_uri) == FALSE) {
+		if (rb_uri_is_descendant (uri, mount_uri) == FALSE) {
 			rb_debug ("uri %s is not under device mount uri %s", uri, mount_uri);
 			return NULL;
 		}

rhythmdb/rhythmdb-monitor.c

@@ -280,7 +280,7 @@ rhythmdb_directory_change_cb (GFileMonitor *monitor,
 
 			/* ignore new files outside of the library locations */
 			for (i = 0; db->priv->library_locations[i] != NULL; i++) {
-				if (g_str_has_prefix (canon_uri, db->priv->library_locations[i])) {
+				if (rb_uri_is_descendant (canon_uri, db->priv->library_locations[i])) {
 					in_library = TRUE;
 					break;
 				}

widgets/rb-import-dialog.c

@@ -431,7 +431,7 @@ current_folder_changed_cb (GtkFileChooser *chooser, RBImportDialog *dialog)
 	locations = g_settings_get_strv (settings, "locations");
 	gtk_widget_set_sensitive (dialog->priv->copy_check, TRUE);
 	for (i = 0; locations[i] != NULL; i++) {
-		if (g_str_has_prefix (uri, locations[i])) {
+		if ((g_strcmp0 (uri, locations[i]) == 0) || rb_uri_is_descendant (uri, locations[i])) {
 			gtk_widget_set_sensitive (dialog->priv->copy_check, FALSE);
 			break;
 		}