More protection for avoiding unnecessary thread re-initialization.
More protection for avoiding unnecessary thread re-initialization.

robbmcleod/numexpr,andreabedini/numexpr,pydata/numexpr,pydata/numexpr,robbmcleod/numexpr,pombredanne/numexpr,andreabedini/numexpr,pombredanne/numexpr,pombredanne/numexpr,andreabedini/numexpr,pydata/numexpr,robbmcleod/numexpr