Revert "do not clean if packages directory is a symlink"
Revert "do not clean if packages directory is a symlink"

This reverts commit 78c4acaa3b459b14d2ebfb4f0f8efa297a792e88.

Y--/jspm-cli,watilde/jspm-cli,jackfranklin/jspm-cli,buddhike/jspm-cli,chenzhenxi/jspm-cli,jspm/jspm-cli,nianwang/jspm-cli,Rush/jspm-cli,Rush/jspm-cli,apiv/jspm-cli,Y--/jspm-cli,watilde/jspm-cli,nfl/jspm-cli,jackfranklin/jspm-cli,wichert/jspm-cli,buddhike/jspm-cli,cgvarela/jspm-cli,Y--/jspm-cli,nfl/jspm-cli,cgvarela/jspm-cli,hmps/jspm-cli,jspm/jspm-cli,chenzhenxi/jspm-cli,Rush/jspm-cli,watilde/jspm-cli,nianwang/jspm-cli,cgvarela/jspm-cli,nianwang/jspm-cli,buddhike/jspm-cli,nfl/jspm-cli,chenzhenxi/jspm-cli,wichert/jspm-cli,apiv/jspm-cli,wichert/jspm-cli,hmps/jspm-cli,jspm/jspm-cli,jackfranklin/jspm-cli,apiv/jspm-cli,hmps/jspm-cli