Although the real issue was that the ruffus pipeline cannot be executed
twice in the same process due to its reliance on global variables.
The new OO pipeline in ruffus 2.6 would be one resolution that would
allow for more comprehensive testing as opposed to farming out the
execution to subprocess and inspecting the results, as is currently
done.
Specifically it trips over the need to reimport ocrmypdf.main. That in
turn raises questions about whether to make that function into an
external script that imports ocrmypdf... or something else. Would be
possible with a loop that manipulates sys_argv and then reloads
ocrmypdf.main; might need that anyway.
