This isn't a bug--you're using the #line directive, so perl's doing what you asked it to, whether you knew you were or not.

The format's more or less:

/^#\s*line\s+(\d+)(.*)/
[download]

where $1 becomes the new line number and $2 the new file name.

Not often used, but it's not a bug. (Though arguably there should've had to have been a space between the number and the name)