As of today, trying to build
apisupport/apidocs/build.xml#parser-db fails (i.e.
creates empty DBs and prints stack traces, though
the target finishes). I put some additional
logging into DataFolder.findFolder and now I see:

java.lang.IllegalArgumentException: Not a
DataFolder:
MultiFileObject@1b60280[nbfs://nbhost/SystemFileSystem/Services]
(was a org.openide.loaders.DefaultDataObject)
(file is folder? false)
        at
org.openide.loaders.DataFolder.findFolder(DataFolder.java:497)
[catch] at
org.netbeans.core.LookupCache.loadDirect(LookupCache.java:83)

where loadDirect is just doing

FileObject services =
Repository.getDefault().getDefaultFileSystem().findResource("Services");
DataFolder servicesF =
DataFolder.findFolder(services);

i.e. for some reason the system file system has
something called "Services", but it is a file
rather than a folder.

This only happens inside this Ant task (run inside
or outside of NB). I checked the list of modules
MakeParserDB.java includes in its CP. Some of them
do have layers and these layers do have Services,
but as a folder, not a file.

I suspected the recent patch to
AbstractFolder.fileCreated0, but I seem to get the
error even after temporarily reverting that.

I am not sure how to track down why the SFS would
consider this a file rather than a folder. Any ideas?