stop passing '.' in @INC to tests

Currently TestInit.pm adds '.' to @INC (except if running under taint).
Since *all* tests run from the perl core are invoked as

    perl -MTestInit[=arg,arg,..] some/test.t

this means that all test scripts (including those under cpan/ etc) are
excuted with dot present, regardless of the settings of
$PERL_USE_UNSAFE_INC and -Ddefault_inc_excludes_dot.

This commit changes it so that:

1) TestInit.pm transparently passes though a trailing dot in @INC
if present (so it now honours $PERL_USE_UNSAFE_INC and
-Ddefault_inc_excludes_dot)
2) Adds a 'DOT' arg (e.g. -MTestInit=DOT) which unconditionally adds '.';
3) Updates t/TEST so that it (and t/harness which requires t/TEST)
have a whitelist of cpan/ modules which need '.'; test scripts for these
are invoked with -MTestInit=DOT.
4) Removes the $PERL_USE_UNSAFE_INC unsetting in t/TEST and t/harness;
now that environmant variable is passed unchanged to all perl processes
involved in running the test suite.

As of this commit, lots of tests will fail on a dotless perl build; the
next few commits will fix up any tests scripts and non cpan/ distributions
which relied on dot being present.

2 files changed, 19 insertions, 4 deletions

diff --git a/t/TEST b/t/TEST
index 6d842d0859..6dc958791c 100755
--- a/t/TEST
+++ b/t/TEST
@@ -76,13 +76,28 @@ my %temp_no_core =
      '../dist/Unicode-Normalize' => 1,
     );
 
+# temporary workaround Apr 2017.  These need '.' in @INC.
+# Ideally this # list will eventually be empty
+
+my %temp_needs_dot  = map { $_ => 1 } qw(
+    ../cpan/ExtUtils-Install
+    ../cpan/Filter-Util-Call
+    ../cpan/libnet
+    ../cpan/Locale-Codes
+    ../cpan/Math-BigInt
+    ../cpan/Math-BigRat
+    ../cpan/Test-Harness
+    ../cpan/Test-Simple
+    ../cpan/version
+);
+
+
 # delete env vars that may influence the results
 # but allow override via *_TEST env var if wanted
 # (e.g. PERL5OPT_TEST=-d:NYTProf)
 my @bad_env_vars = qw(
     PERL5LIB PERLLIB PERL5OPT
     PERL_YAML_BACKEND PERL_JSON_BACKEND
-    PERL_USE_UNSAFE_INC
 );
 
 for my $envname (@bad_env_vars) {
@@ -245,6 +260,9 @@ sub _scan_test {
 		if ($temp_no_core{$run_dir}) {
 		    $testswitch = $testswitch . ',NC';
 		}
+		if($temp_needs_dot{$run_dir}) {
+		    $testswitch = $testswitch . ',DOT';
+		}
 	    }
 	} elsif ($test =~ m!^\.\./lib!) {
 	    $testswitch = '-I.. -MTestInit=U1'; # -T will remove . from @INC
diff --git a/t/harness b/t/harness
index e06c3f8009..b46582ddd9 100644
--- a/t/harness
+++ b/t/harness
@@ -34,9 +34,6 @@ if ($ARGV[0] && $ARGV[0] eq '-torture') {
 # which live dual lives on CPAN.
 $ENV{PERL_CORE} = 1;
 
-# All our tests should work without . in @INC
-delete $ENV{PERL_USE_UNSAFE_INC};
-
 my (@tests, $re);
 
 # [.VMS]TEST.COM calls harness with empty arguments, so clean-up @ARGV