not true. 6.51 has no game breaking bugs.
the one you are mentioning, is a bug exclusive to 6.51 1.52 AI+ by RGB Ported by BuffMePlz (Revision 1).
IIRC, it is fixed in revision 2 which is the latest.
6.51 is not a stable map. probably it wont even be a pseudo-stable map (like 6.43b).
most leagues/tourneys right now are using 6.49c because the radical changes between these versions...esp. the dagger. many still whine about it, they can do all they want. but Ice said it specifically, it IS here to stay just like deny-exp/aegis changes.
Going by the past trend, next official stable will be some thing like ~6.58.
and the Pseudo-Stable might be 6.52b.