Reset SDK deps back to develop after a release

This automates the (frequently forgotten) step of resetting SDK deps back to the
develop branch after merging the release to develop.

release.sh

@@ -44,11 +44,17 @@ do
     fi
 done
 
-# bump Electron's package.json first
 release="${1#v}"
 tag="v${release}"
-echo "electron yarn version"
+prerelease=0
+# We check if this build is a prerelease by looking to
+# see if the version has a hyphen in it. Crude,
+# but semver doesn't support postreleases so anything
+# with a hyphen is a prerelease.
+echo $release | grep -q '-' && prerelease=1
 
+# bump Electron's package.json first
+echo "electron yarn version"
 cd electron_app
 yarn version --no-git-tag-version --new-version "$release"
 git commit package.json -m "$tag"
@@ -56,3 +62,16 @@ git commit package.json -m "$tag"
 cd ..
 
 exec ./node_modules/matrix-js-sdk/release.sh -u vector-im -z "$orig_args"
+
+if [ $prerelease -eq 0 ]
+then
+    # For a release, reset SDK deps back to the `develop` branch.
+    for i in matrix-js-sdk matrix-react-sdk
+    do
+        echo "Resetting $i to develop branch..."
+        yarn add github:matrix-org/$i#develop
+        git add -u
+        git commit -m "Reset $i back to develop branch"
+    done
+    git push origin develop
+fi