Nonexistent input file name gives misleading error message

[Geoff Horton]

Assuming that there's no such file as "asdfg.ly", typing:

lilypond asdfg.ly

gives as output:

warning: can't find file: `'
error: failed files: "asdfg.ly"

This makes it appear that the file exists (it failed, after all) but
has a bad \include in it somewhere--I just spent a good twenty minutes
trying to fix a file that wasn't broken (at least in that respect). Is
there any particular reason it doesn't say "can't find file
`asdfg.ly'" instead?

This happens in 2.8 on both WinXP and Linux.

Geoff