tests: fix love.filesystem mounting

src/modules/filesystem/physfs/Filesystem.cpp

@@ -232,6 +232,8 @@ bool Filesystem::setIdentity(const char *ident, bool appendToPath)
 	// This is done so the save directory is only created on-demand.
 	if (!mountCommonPathInternal(COMMONPATH_APP_SAVEDIR, nullptr, MOUNT_PERMISSIONS_READWRITE, appendToPath, false))
 		saveDirectoryNeedsMounting = true;
+	else
+		saveDirectoryNeedsMounting = false;
 
 	// Mount any other app common paths with directory creation immediately
 	// instead of on-demand, since to get to this point they would have to be

testing/tests/filesystem.lua

@@ -410,7 +410,7 @@ love.test.filesystem.mountCommonPath = function(test)
   end
   local mount6 = love.filesystem.mountCommonPath('userdocuments', 'userdocuments', 'readwrite')
   local ok = pcall(love.filesystem.mountCommonPath, 'fakepath', 'fake', 'readwrite')
-  test:assertTrue(mount1, 'check mount appsavedir')
+  test:assertFalse(mount1, 'check mount appsavedir') -- This is already mounted, we can't do it again.
   test:assertTrue(mount2, 'check mount appdocuments')
   test:assertTrue(mount3, 'check mount userhome')
   test:assertTrue(mount4, 'check mount userappdata')