Add transfer-branch command

Author: atimmer

package.json

@@ -18,6 +18,7 @@
     "test": "lerna run test --stream",
     "install-ci": "lerna run install-ci",
     "link-all": "lerna exec yarn link",
-    "unlink-all": "lerna exec yarn unlink"
+    "unlink-all": "lerna exec yarn unlink",
+    "transfer-branch": "./transfer-branch.sh"
   }
 }

transfer-branch.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+
+set -ex;
+
+PACKAGE=$1
+BASE_BRANCH=$2
+MERGING_BRANCH=$3
+
+if [ -z "$MERGING_BRANCH" ]; then
+    echo "Usage: yarn transfer-branch [package] [base-branch] [merging-branch]";
+    exit 1;
+fi
+
+case $PACKAGE in
+"yoastseo")
+    ORIGINAL_REPOSITORY=https://github.com/Yoast/YoastSEO.js.git
+    ;;
+"yoast-components")
+    ORIGINAL_REPOSITORY=https://github.com/Yoast/yoast-components.git
+    ;;
+esac
+
+if [ -z "$ORIGINAL_REPOSITORY" ]; then
+    echo "Error: Unknown package";
+    exit 1;
+fi
+
+echo $ORIGINAL_REPOSITORY;
+
+git checkout $BASE_BRANCH
+git checkout -b $MERGING_BRANCH
+
+git subtree pull --prefix=packages/$PACKAGE $ORIGINAL_REPOSITORY $MERGING_BRANCH