Use minimal @INC in tests, most of the time just '../lib',

so that we simply can't pick up stuff from other Perls than
the one we are testing.  Pointed out by
Subject: Re: [PATCH: 6757] make new Storable tests forgiving of places where not built   
Message-Id: <E13SKH1-00031D-00@virgo.cus.cam.ac.uk>

p4raw-id: //depot/perl@6874

5 files changed, 5 insertions, 5 deletions

diff --git a/t/io/argv.t b/t/io/argv.t
index 2595fa681c..2b8f23b426 100755
--- a/t/io/argv.t
+++ b/t/io/argv.t
@@ -2,7 +2,7 @@
 
 BEGIN {
     chdir 't' if -d 't';
-    unshift @INC, '../lib';
+    @INC = '../lib';
 }
 
 print "1..21\n";
diff --git a/t/io/fs.t b/t/io/fs.t
index 970e2f32ae..7182c2496b 100755
--- a/t/io/fs.t
+++ b/t/io/fs.t
@@ -4,7 +4,7 @@
 
 BEGIN {
     chdir 't' if -d 't';
-    unshift @INC, '../lib';
+    @INC = '../lib';
 }
 
 use Config;
diff --git a/t/io/open.t b/t/io/open.t
index 30db5988b6..b224cceb77 100755
--- a/t/io/open.t
+++ b/t/io/open.t
@@ -2,7 +2,7 @@
 
 BEGIN {
     chdir 't' if -d 't';
-    unshift @INC, '../lib';
+    @INC = '../lib';
 }    
 
 # $RCSfile$    
diff --git a/t/io/openpid.t b/t/io/openpid.t
index 80c6bde5d1..d8326d8e63 100755
--- a/t/io/openpid.t
+++ b/t/io/openpid.t
@@ -9,7 +9,7 @@
 
 BEGIN {
     chdir 't' if -d 't';
-    unshift @INC, '../lib';
+    @INC = '../lib';
     if ($^O eq 'dos') {
         print "1..0 # Skip: no multitasking\n";
         exit 0;
diff --git a/t/io/pipe.t b/t/io/pipe.t
index 4559624cca..96935e3f88 100755
--- a/t/io/pipe.t
+++ b/t/io/pipe.t
@@ -2,7 +2,7 @@
 
 BEGIN {
     chdir 't' if -d 't';
-    unshift @INC, '../lib';
+    @INC = '../lib';
     require Config; import Config;
     unless ($Config{'d_fork'}) {
 	print "1..0 # Skip: no fork\n";