1. do you have a reference (a bug report, etc.) for pdftops returning nonzero?
2. perhaps we should just always take whatever comes out on stdout, as long as it matches the regex, and ignore whether the return code is zero or not?

1. do you have a reference (a bug report, etc.) for pdftops returning nonzero?

Unfortunately I couldn't find a public bug report. The problem encountered here was detected with Homebrew's xpdf package (version 4.01.01), because of the following code in xpdf/pdftops.cc:

  ok = parseArgs(argDesc, &argc, argv);
  if (!ok || argc < 2 || argc > 3 || printVersion || printHelp) {
    fprintf(stderr, "pdftops version %s\n", xpdfVersion);
    fprintf(stderr, "%s\n", xpdfCopyright);
    if (!printVersion) {
      printUsage("pdftops", "<PDF-file> [<PS-file>]", argDesc);
    }
    exit(1);
  }

In other words, even if -v is the only command-line argument explicitly demanded and nothing else is wrong, the program will exit as if there were a problem with the cmdline. (I'll file a separate bug report to xpdf developers).

If the ps back-end is used and ps.usedistiller is set to "xpdf", this problem can be triggered at import time.

Seems fair.

While this is suppressing a CalledProcessError it's actually the exist code that determines this, so maybe better call it ignore_exit_code?

This is good suggestion and I've updated accordingly (and force-pushed after rebasing).

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

$ git checkout v2.2.x
$ git pull

1. Cherry pick the first parent branch of the this PR on top of the older branch:

$ git cherry-pick -m1 fd9c59dc54be14077dd0124c3046a99526bf188a

1. You will likely have some merge/cherry-pick conflict here, fix them and commit:

$ git commit -am 'Backport PR #14395: MAINT: work around non-zero exit status of "pdftops -v" command.'

1. Push to a named branch :

git push YOURFORK v2.2.x:auto-backport-of-pr-14395-on-v2.2.x

1. Create a PR against branch v2.2.x, I would have named this PR:

"Backport PR #14395 on branch v2.2.x"

And apply the correct labels and milestones.

Congratulation you did some good work ! Hopefully your backport PR will be tested by the continuous integration and merged soon!

If these instruction are inaccurate, feel free to suggest an improvement.

Thanks @congma !

This code path is not in 2.2.x, it came in via 32ed5bd which is in 3.0+.