Instead of:
C:\Users\Ganesh\AppData\Local\Temp\data-default-instances-old-locale-0.0.1-11924\data-default-instances-old-locale-0.0.1
(which was the case before @ezyang's patch)
we now get:
C:\Users\Ganesh\AppData\Local\Temp\cabal-tmp-11924\data-default-instances-old-locale-0.0.1

Fixes #2658.