couldn't find HOME environment variable when expanding '~' (ArgumentError)

[eregon]

It seems CRuby has a fallback in the case HOME is unset:

$ unset HOME          
$ ruby -e 'p Dir.home'
"/home/eregon"
$ HOME=/home ruby -e 'p Dir.home'
"/home"

Found in SeleniumHQ/selenium#11251 (comment)

Related: jruby/jruby#5661

[p0deje]

Fixing this would also make Bazel rules for Ruby a bit easier - bazel-contrib/rules_ruby@80b362c