Don't copy all of %ENV in prereq.t.

It's sufficient for purposes of enabling prerequisite warnings to
set a localized $ENV{PERL_CORE} to undef rather than making a local
copy of the entire %ENV hash.  This makes the test pass on VMS,
where copying %ENV in toto is not supported.

This fixes a smoke failure, so borrow it from upstream, where it's
already released as part of MM 6.57_10.  6.58 will contain an
additional tweak that works with Perl 5.6, but no need to worry
about that here.

diff --git a/cpan/ExtUtils-MakeMaker/t/prereq.t b/cpan/ExtUtils-MakeMaker/t/prereq.t
index 13e354a..094fee7 100644 (file)
--- a/cpan/ExtUtils-MakeMaker/t/prereq.t
+++ b/cpan/ExtUtils-MakeMaker/t/prereq.t
@@ -35,9 +35,8 @@ ok( chdir 'Big-Dummy', "chdir'd to Big-Dummy" ) ||
     local $SIG{__WARN__} = sub {
         $warnings .= join '', @_;
     };
-    # prerequisite warnings are disbled while building the perl core:
-    local %ENV = %ENV;
-    delete $ENV{PERL_CORE};
+    # prerequisite warnings are disabled while building the perl core:
+    local $ENV{PERL_CORE} = undef;
 
     WriteMakefile(
         NAME            => 'Big::Dummy',