cet-is » art

A file
FN=/pnfs/mu2e/scratch/users/rlc/dig.owner.val-ceMixDigi.dsconf.seq.art
produced by a mixing job has events:

> count_events $FN
/pnfs/mu2e/scratch/users/rlc/dig.owner.val-ceMixDigi.dsconf.seq.art     1      1    10      0
and products:
 > artProductSizes $FN
Number of entries:  10
        Size     Size/Entry   Fraction  Data Product Name
     (bytes)       (bytes)

      805199        80519.9      0.408  mu2e::StrawDigis_makeSD__ceMixDigi.
      359470        35947.0      0.182  mu2e::StepPointMCs_detectorFilter_calori
...

But when I run a job with a simple, stable module:

> mu2e --trace -c Print/fcl/dumpDataProducts.fcl -s $FN

it finds no events:

++ Job started
++++open input file
++++finished: open input file /pnfs/mu2e/scratch/users/rlc/dig.owner.val-ceMixDigi.dsconf.seq.art
++++close output file from dump
++++finished close output file <none> from dump
++++close input file
...
Art has completed and will exit with status 0.

I can produce and read non-mixed files in this build.

To reproduce
source /cvmfs/mu2e.opensciencegrid.org/setupmu2e-art.sh
git clone http://cdcvs.fnal.gov/projects/mu2eofflinesoftwaremu2eoffline/Offline.git
cd Offline
git checkout -b temp 72f3b6b32814
source setup.sh
scons -j 20 >& build.log
mu2e --trace -c Print/fcl/dumpDataProducts.fcl -s $FN