Error on renaming when engine contains /

[mgkurtz]

I am currently adding some regression tests to pdfjam using l3build. Indeed this works pretty well and needs only those two lines in l3build.lua:

checkengines = {"engine"} -- small wrapper script to use `pdfjam` with `l3build`
pvtext = ".args" -- *.args files contain command line arguments for `pdfjam`

as long as engine lies in my search PATH.

I would like this to work as well, if I put engine in testfiles/support and use checkengines = {"./engine"}. Alas at several places in l3build-check.lua, we compute a file name using "." .. engine which leads to the error

mv: cannot move './build/result/demo.pdf' to './build/result/demo../engine.pdf': No such file or directory

This should be avoidable by always using "." .. basename(engine) instead of "." .. engine.