ruby - stdlib Pathname#relative_path_from does not support mixed directory separators on windows

Question

The support for mixing backslashes and forward slashes in the pathname module in the standard library seems to be broken on windows

require 'pathname'
base = Pathname.new("c:\\")
filepath = Pathname.new("c:/foo/bar/file.ext")
base.relative_path_from(filepath)

raises ArgumentError: different prefix: "c:\\" and "c:/foo/bar/file.ext"

Changing filepath to contain backslashes fixes the problem

filepath = Pathname.new("c:\\foo\\bar\\file.ext")
base.relative_path_from(filepath)

=> #<Pathname:../../..>