Fix variable name type on post import hook discovery.
Fix variable name type on post import hook discovery.

linglaiyao1314/wrapt,linglaiyao1314/wrapt,pombredanne/wrapt,GrahamDumpleton/wrapt,GrahamDumpleton/wrapt,github4ry/wrapt,pombredanne/wrapt,wujuguang/wrapt,akash1808/wrapt,github4ry/wrapt,wujuguang/wrapt,akash1808/wrapt