hexl-mode doesn't seem to allow me to create a binary file.

Steps:
1. Open Emacs
2. Create a new file using C-x C-f /tmp/boot-sect.bin
3. M-x hexl-mode
4. M-x hexl-insert-hex-char
5. e
6. Nothing is written into the buffer and the message buffer says "Point is
not on a character file".

I took a brief look at the source code and it appears
that (hexl-current-address) expected the cursor to not be in the top left
(0,0) location of the buffer.  Normally in hexl-mode those columns are
going to be occupied by addresses.  Yet, that's exactly where the cursor is
because that's an empty file.

I tried on my two Macs and on a Linux box too.
It works as expected if I do "echo 0 > /tmp/boot-sect.bin" first so that
the file isn't empty.

Cheers,
Igor
-----

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hexl-current-address: Point is not on a character in the file

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