forked origin requires a forked destination

Fixes: https://code.forgejo.org/actions/cascading-pr/issues/10

cascading-pr-lib.sh

@@ -115,6 +115,18 @@ function scheme() {
     echo "${url%%://*}"
 }
 
+function owner() {
+    local repo="$1"
+
+    echo "${repo%%/*}"
+}
+
+function repository() {
+    local repo="$1"
+
+    echo "${repo##*/}"
+}
+
 function get_status() {
     local api="$1"
     local sha="$2"