Add custom command to Fork that copies commit to upstream without disturbing current working tree

.fork/custom-commands.json

@@ -0,0 +1,15 @@
+[
+  {
+    "version" : 2
+  },
+  {
+    "action" : {
+      "script" : "git worktree add .temp-worktree upstream/main\ncd .temp-worktree\ngit cherry-pick ${sha}\ngit push upstream HEAD:main\ncd ..\ngit worktree remove .temp-worktree",
+      "showOutput" : false,
+      "type" : "sh",
+      "waitForExit" : true
+    },
+    "name" : "Cherry-pick and push to upstream",
+    "target" : "revision"
+  }
+]