Add a clean_browserdir option

If this option is set to true (the default), the browser source dir is
cleaned before doing the checkout.

This option is mainly useful for testing/debugging the testsuite.

TBBTestSuite/BrowserUnitTests.pm

@@ -9,6 +9,7 @@ use File::Copy;
 use File::Slurp;
 use TBBTestSuite::Common qw(exit_error get_nbcpu run_to_file);
 use TBBTestSuite::Reports qw(load_report);
+use TBBTestSuite::Options qw($options);
 
 my $test_types = {
     xpcshell => \&xpcshell_test,
@@ -45,8 +46,10 @@ sub get_tbbinfos {
 sub pre_tests {
     my ($tbbinfos) = @_;
     chdir $tbbinfos->{browserdir};
-    system('git', 'clean', '-fxd');
-    system('git', 'reset', '--hard');
+    if ($options->{clean_browserdir}) {
+        system('git', 'clean', '-fxd');
+        system('git', 'reset', '--hard');
+    }
     system('git', 'checkout', $tbbinfos->{commit}) == 0
         or exit_error "Error checking out $tbbinfos->{commit}";
     my ($out, $err, $success) = capture_exec('git', 'show', '-s',

TBBTestSuite/Options.pm

@@ -25,6 +25,7 @@ my %default_options = (
     selenium => $OSNAME ne 'cygwin',
     starttor => 1,
     gpgcheck => 1,
+    clean_browserdir => 1,
     keyring  => 'erinn.gpg',
     'tor-control-port' => '9551',
     'tor-socks-port'   => '9550',