Due to an issue in handling thread-local storages, os/user can lead to SEGV
when glibc is statically linked with.
So we prefer os.Getenv("HOME") for guessing where is the home directory.
See also: golang/go#13470
Change-Id: I1046ff93a71aa3b11299f7e6cf65ff7b1fb07eb9
Reviewed-on: https://go-review.googlesource.com/34175
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>