When I run validate --slow a number of tests fail, apparently erroneously, because GhostScript not available for hp2ps tests.

I don't know why this is the case (Ghostscript is installed on my ubuntu; perhaps there are some developer libraries / headers that also need to be installed, but I don't recall seeing anything in the documentation about that).

The message "GhostScript not available for hp2ps tests" seems to come from a Python script that Simon Marlow produced in 2002. Unfortunately, there are two places where the message could have been generated.

There are probably 2 ways forward:

• a temporary bodge: taking the running of those tests that depend on hp2ps out of validation, in the same way that certain tests are not run when a dependent library is unavailable

• figuring out why the python script fails to understand that a ghostscript is actually present and fixing that