flock(2) on an NFS mount will on the server side convert the lock to a
POSIX lock (fcntl(F_SETLK)). This means that abuild running on NFS
server and client will create different locks and they will both try
download same file at same time.
We fix this by creating a small abuild-fetch application that will
create a POSIX lock which works with NFS.
Natanael Copa