affectedRows can't be checked in 3.1.4

Since 3.1.4 the MySQL Connection get's closed: https://github.com/silverstripe/silverstripe-framework/commit/912cda9a1e4a9527c20a08e59ffcc8adb7a9257c#diff-dcae344d3072fe9767a7a6c3b45ec815

This leads to an error when calling DB::affectedRows() here. Since I see no dramatic harm in flushing the Cache i just removed the check for changes and all it every time.