Tabs are not allowed in Bugzilla source... if we find one, issue a warning.

t/005whitespace.t

+# -*- Mode: perl; indent-tabs-mode: nil -*-
+#
+# The contents of this file are subject to the Mozilla Public
+# License Version 1.1 (the "License"); you may not use this file
+# except in compliance with the License. You may obtain a copy of
+# the License at http://www.mozilla.org/MPL/
+#
+# Software distributed under the License is distributed on an "AS
+# IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
+# implied. See the License for the specific language governing
+# rights and limitations under the License.
+#
+# The Original Code are the Bugzilla tests.
+#
+# The Initial Developer of the Original Code is Jacob Steenhagen.
+# Portions created by Jacob Steenhagen are
+# Copyright (C) 2001 Jacob Steenhagen. All
+# Rights Reserved.
+#
+# Contributor(s): Jacob Steenhagen <jake@acutex.net>
+#
+
+#################
+#Bugzilla Test 4#
+#####no_tabs#####
+
+BEGIN { use lib "t/"; }
+BEGIN { use Support::Files; }
+BEGIN { $tests = @Support::Files::testitems; }
+BEGIN { use Test::More tests => $tests; }
+
+my @testitems = @Support::Files::testitems;
+my $verbose = $::ENV{VERBOSE};
+
+foreach my $file (@testitems) {
+    open (FILE, "$file");
+    my @file = <FILE>;
+    close (FILE);
+    if (grep /\t/, @file) {
+        ok(0, "$file contains tabs --WARNING");
+    } else {
+        ok(1, "$file has no tabs");
+    }
+}
+