[syslinux] Mkdiskimage exits with syntax (maybe drive letter problem?)

[Nazo]

I have had a problem with mkdiskimage for quite a while.  It seems to
always exit with the syntax messages.  I'm not really familiar enough
with Perl to figure out exactly what it's checking for there that it
determines is incorrect, but, my guess would have to be that it
doesn't like the letter.  Eg, I think the last time it suceeded I was
running it on sda, but, not I'm typically running it on sdb or even
hdb.

If I remove the "exit 1" command from line 110, then the program will
continue and format the drive in as nearly as I can tell correct
manner (at least it seemed to in my previous attempts.)

Am I missing something, or is the check maybe not working 100% correctly?