would it not just produce 'b/c'? assuming 'b/c' is an existent file path
what else could you justify it doing?
What sibling comment says. Bash does suppress nonexistent products when the pattern includes a glob metacharacter and `shopt -s nullglob' is in effect, but I didn't see a flag or anything to achieve that in the project README.
The behavior of bash would be to produce "a/c" and "b/c", even if both files don't exist