When running the WebGUI tests under prove, every test would spew this warning:
Devel::Cover: Can't open -e for MD5 digest: No such file or directory
They were just warnings, but they really cluttered up the prove output. Google didn't reveal anything except that the parrot tests showed the same problem. Nothing in rt.cpan.org or cpanforums.com.
I tried pulling out FindBin (something that parrot also uses) but it didn't
help. Finally, by chance, while reading the Devel::Cover POD I noticed that
the preferred way of using it is to set
PERL5OPT. Sure enough, that made the warnings go