bug-compatible
Said of a design or revision that has been badly compromised
by a requirement to be compatible with {fossil}s or
{misfeature}s in other programs or (especially) previous
releases of itself. "{MS-DOS} 2.0 used \ as a path separator
to be bug-compatible with some cretin's choice of / as an
option character in 1.0."
[{Jargon File}]