Puppet cannot store empty files into filebucket

Steps to reproduce:

1. Configure a master and an agent (can be on a single machine)
2. Create an empty file
3. Try to backup the file

Expected behaviour: The file is stored in the filebucket
Actual behaviour: Error 400 is raised

root@petest:/tmp# >tstfile

root@petest:/tmp# puppet filebucket backup /tmp/tstfile        

Error: Could not back up /tmp/tstfile: Error 400 on SERVER: No data to save

Error: Could not run: Could not back up /tmp/tstfile: Error 400 on SERVER: No data to save

When run with a local filebucket everything looks good:

root@petest:/tmp# puppet filebucket backup /tmp/tstfile --local

/tmp/tstfile: d41d8cd98f00b204e9800998ecf8427e

When there's content in the file it looks good as well:

root@petest:/tmp# echo Hello >tstfile

root@petest:/tmp# puppet filebucket backup /tmp/tstfile

/tmp/tstfile: 09f7e02f1290be211da707a266f153b3

This happens in the following version (not sure what is the first affected version):

root@petest:/tmp# puppet --version

3.3.1 (Puppet Enterprise 3.1.0-rc1-3-geacb9a8)

This looks like a major bug since any content change on a file that's empty prevents the catalog from successful applying.

Note: The same operation works fine with PE 2.8.1