[FIX] modules: In some cases (e.g. when using module_file) the module's groups are already unserialised (thanks marclaporte)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/11.x@46937 b456876b-0849-0410-b77d-98878d47e9d5
[MRG] Automatic merge, branches/11.x 46930 to 46937

git-svn-id: file:///var/local/code.tiki.org/tikisvn/trunk@46938 b456876b-0849-0410-b77d-98878d47e9d5