Tag editor: only write files with modified tags (#536)

src/screens/tag_editor.cpp

@@ -797,6 +797,8 @@ void TagEditor::runAction()
 			bool success = 1;
 			Statusbar::print("Writing changes...");
 			for (auto it = EditedSongs.begin(); it != EditedSongs.end(); ++it)
+			{
+				if ((*it)->isModified())
 				{
 					Statusbar::printf("Writing tags in \"%1%\"...", (*it)->getName());
 					if (!Tags::write(**it))
@@ -807,6 +809,7 @@ void TagEditor::runAction()
 						break;
 					}
 				}
+			}
 			if (success)
 			{
 				Statusbar::print("Tags updated");