Avoid `user.Current` if possible to avoid glibc bug
Avoid `user.Current` if possible to avoid glibc bug

Attempt to use `$HOME` to find the user's home directory to avoid calling
`user.Current`, which can runtime panic due to a known glib bug. This emulates
the fix in https://go-review.googlesource.com/c/oauth2/+/34175, to work around
http://golang.org/issue/13470

lib/pq,VividCortex/pq