##
$ perl -e'require "MAS::Global";' # Bad
Can't locate MAS::Global in @INC [...] at -e line 1.
$ perl -e'require MAS::Global;' # Ok
Can't locate MAS/Global.pm in @INC [...] at -e line 1.
$ perl -e'require "MAS/Global.pm";' # Ok
Can't locate MAS/Global.pm in @INC [...] at -e line 1.
####
# Equivalent to what `if.pm` uses.
my $require_path = $pkg_name =~ s{::}{/}gr . ".pm";