matplotlib plotting failing

[teuben]

Most plotting (see docs/plotting.md) in the pipeline is done in batch mode, a plotfile (png or pdf) is choosen as output.

But as of some time ago, and this has gotten worse with ubuntu24, this can fail if the backend isn't hardcoded.

Failure mode can then depend on running via sbatch (which uses Xvfb) and "interactive" via make. Example for RSR is the "make bench1" method vs. using etc/bench1.run:

                          make bench1          sbatch_lmtoy.sh etc/bench1.run

tsys                       FAIL                        OK
badlags                OK                           OK
waterfall               OK                          FAIL
final                       FAIL                        OK

It should be noted that "make bench1" on a non-unity system always works in these 4 modes.

[teuben]

The two failing in interactive mode had the usual fix to matplotlib using agg.

The failure in sbatch was due to /usr/bin/convert not able to convert PDF to PNG in Ubuntu24, which worked in U20.

[teuben]

The error in convert has gone away after changing the old module load from

    module load uri/main Xvfb/1.20.13-GCCcore-11.2.0

to

    module load uri/main