copy-rectangle-to-register and picture-yank-rectangle-from-register

[ed park]

GNU Emacs 20.7.2 (i386-*-nt4.0.1381) of Mon Nov 27 2000 on buffy;
windows nt 4.0 sp 5.

(also occurs using:
GNU Emacs 20.4.1 (i386-*-nt4.0.1381) of Thu Jul 15 1999 on gridlock;
with windows me.)

when i twice use copy-rectangle-to-register and
picture-yank-rectangle-from-register to overwrite a
column of characters, i get the expected result the
first time, and a different and unexpected result the
second time.

to reproduce:

start emacs using runemacs -q.

open a buffer called test.

insert the following ten lines of text in buffer test:

abcd   ;line 1
abcd   ;line 2
abcd   ;line 3
abcd   ;line 4
abcd   ;line 5
abcd   ;line 6          
    
1  2   ;line 8
1  2   ;line 9
1  2   ;line 10

M-x load-library picture.

place the cursor on the 1 in line 8 and M-x
set-mark-command.

place the cursor on the space after the 1 on line 10
and M-x copy-rectangle-to-register t.
 
place the cursor on the 2 in line 8 and M-x
set-mark-command.

place the cursor on the space after the 2 on line 10
and M-x copy-rectangle-to-register u.
 
place the cursor on the a in line 1 and M-x
picture-yank-rectangle-from-register t.  (this produces
the expected result; the a's in lines 1-3 are replaced
by 1's.)

place the cursor on the a in line 4 and M-x
picture-yank-rectangle-from-register u.  (this produces
a different and unexpected result; both the a's *and
the b's* in lines 4-6 are replaced by 2's, so that the
buffer now looks like this:

1bcd   ;line 1
1bcd   ;line 2
1bcd   ;line 3
2cd   ;line 4
2cd   ;line 5
2cd   ;line 6          
    
1  2   ;line 8
1  2   ;line 9
1  2   ;line 10