Looks like a repro to me.
This is the sign they were knocking off, although I suspect this might be bogus despite the rust and chipped paint:
http://www.ebay.com/itm/261408191000
I have seen three different examples of this sign.
1. was a definite repro, thin metal small corner holes
2. was heavy gauge metal with larger corner holes and better quality paint it seemed to be an earlier repro { possibly a later original sign but most likely repro.}
and sign #3 was about 8 or 10" square and was a very nice original porcelain sign.
This sign looks like #2, the damage to the metal and paint would appear different if it was #1.
I am interested in a porcelain example of this sign.
Jim