diff --git a/core/shipped.json b/core/shipped.json
index 717e433e017c..eb514f733b3a 100644
--- a/core/shipped.json
+++ b/core/shipped.json
@@ -3,7 +3,6 @@
     "encryption",
     "configreport",
     "dav",
-    "enterprise_key",
     "federation",
     "federatedfilesharing",
     "files",
diff --git a/lib/private/Installer.php b/lib/private/Installer.php
index 2ebeda117b42..a41ac1e1dc80 100644
--- a/lib/private/Installer.php
+++ b/lib/private/Installer.php
@@ -429,16 +429,21 @@ public static function isDownloaded( $name ) {
 	public static function removeApp($appId) {
 
 		if(Installer::isDownloaded( $appId )) {
-			$appDir=OC_App::getInstallPath() . '/' . $appId;
+			$appDir = OC_App::getAppPath($appId);
+			if ($appDir === false) {
+				return false;
+			}
+			if(is_dir("$appDir/.git")) {
+				throw new AppAlreadyInstalledException("App <$appId> is a git clone - it will not be deleted.");
+			}
+
 			OC_Helper::rmdirr($appDir);
 
 			return true;
-		}else{
-			\OCP\Util::writeLog('core', 'can\'t remove app '.$appId.'. It is not installed.', \OCP\Util::ERROR);
-
-			return false;
 		}
+		\OCP\Util::writeLog('core', 'can\'t remove app '.$appId.'. It is not installed.', \OCP\Util::ERROR);
 
+		return false;
 	}
 
 	/**
diff --git a/lib/private/legacy/app.php b/lib/private/legacy/app.php
index 4507e8bc292a..9f48dcb9c682 100644
--- a/lib/private/legacy/app.php
+++ b/lib/private/legacy/app.php
@@ -359,6 +359,9 @@ public static function enable($app, $groups = null) {
 		$config = \OC::$server->getConfig();
 		$l = \OC::$server->getL10N('core');
 		$info = self::getAppInfo($app);
+		if ($info === null) {
+			throw new \Exception("$app can't be enabled since it is not installed.");
+		}
 
 		self::checkAppDependencies($config, $l, $info);
 
diff --git a/lib/public/App/IAppManager.php b/lib/public/App/IAppManager.php
index f2f24cff63b1..b6d64aa4d920 100644
--- a/lib/public/App/IAppManager.php
+++ b/lib/public/App/IAppManager.php
@@ -116,10 +116,11 @@ public function getAlwaysEnabledApps();
 
 	/**
 	 * @param string $package
+	 * @param bool $skipMigrations whether to skip migrations, which would only install the code
 	 * @return mixed
 	 * @since 10.0
 	 */
-	public function installApp($package);
+	public function installApp($package, $skipMigrations = false);
 
 	/**
 	 * @param string $package