https://github.com/NetHack/NetHack/pull/573 by entrez
Pull request comment states:
"Moving into a position containing a warning symbol with m-<direction> to
'safely' move would still attack as though the 'm' prefix was not
specified. Ensure warning symbols are counted as 'detected' monsters
for this purpose, to avoid falling through to do_attack()."
Closes#573
Michael Meyer
121290cde6