Recieve multiple users from backend for user sync

Recieve multiple users from the backend for user sync
instead of checking for single user. From the received
users check if the user to be synced is available in
the list.

Signed-off-by: Sujith H <sharidasan@owncloud.com>

Author: sharidas

core/Command/User/SyncBackend.php

@@ -252,15 +252,23 @@ private function syncSingleUser(
 		$missingAccountsAction
 	) {
 		$output->writeln("Syncing $uid ...");
-		$users = $backend->getUsers($uid, 2);
-		if (\count($users) > 1) {
-			throw new \LengthException("Multiple users returned from backend for: $uid. Cancelling sync.");
+		$users = $backend->getUsers($uid);
+		$userToSync = null;
+		foreach ($users as $user) {
+			if ($backend->getDisplayName($user) === $uid) {
+				if ($userToSync === null) {
+					$userToSync = $user;
+				} else {
+					throw new \LengthException("Multiple users returned from backend for: $uid. Cancelling sync.");
+				}
+			}
 		}
 
 		$dummy = new Account(); // to prevent null pointer when writing messages
-		if (\count($users) === 1) {
+
+		if ($userToSync !== null) {
 			// Run the sync using the internal username if mapped
-			$syncService->run($backend, new \ArrayIterator([$users[0]]), function () {
+			$syncService->run($backend, new \ArrayIterator([$userToSync]), function () {
 			});
 		} else {
 			// Not found

tests/lib/Command/User/SyncBackendTest.php

@@ -276,7 +276,9 @@ public function testSingleUserSyncExistingUserException() {
 		$outputInterface = $this->createMock(OutputInterface::class);
 		$syncService = $this->createMock(SyncService::class);
 
-		$this->dummyBackend->method('getUsers')->willReturn(['existing-uid', 'should-explode']);
+		$this->dummyBackend->method('getUsers')->willReturn(['existing-uid', 'existing-uid']);
+		$this->dummyBackend->method('getDisplayName')
+			->willReturn('existing-uid');
 
 		$missingAccountsAction = 'disable';
 		$syncService->expects($this->never())->method('run');
@@ -297,6 +299,8 @@ public function testSingleUserSyncExistingUser() {
 		$syncService = $this->createMock(SyncService::class);
 
 		$this->dummyBackend->method('getUsers')->willReturn(['existing-uid']);
+		$this->dummyBackend->method('getDisplayName')
+			->willReturn('existing-uid');
 
 		$missingAccountsAction = 'disable';
 		$syncService->expects($this