Fix bug introduced in fac8ecbbafde17dd92439c41747223c43e9d2b80
Fix bug introduced in fac8ecbbafde17dd92439c41747223c43e9d2b80

Fixes recent failures in hGetBuf001.

ilyasergey/GHC-XAppFix,ilyasergey/GHC-XAppFix,ilyasergey/GHC-XAppFix,ilyasergey/GHC-XAppFix