address review comments

mysql-test/collections/README.experimental

@@ -11,7 +11,7 @@ The syntax is as follows:
 
 2) Empty lines and lines starting with a hash (#) are ignored.
 
-3) If any other line contains a black followed by a hash (#), the hash 
+3) If any other line contains a blank followed by a hash (#), the hash 
    and any subsequent characters are ignored.
 
 4) The full test case name including the suite and execution mode

mysql-test/lib/mtr_report.pm

@@ -123,14 +123,20 @@ sub mtr_report_test ($) {
     {
       # Find out if this test case is an experimental one, so we can treat
       # the failure as an expected failure instead of a regression.
-      for my $exp ( @$::opt_experimental ) {
+      for my $exp ( @$::experimental_test_cases ) {
         if ( $exp ne $test_name ) {
+          # if the expression is not the name of this test case, but has
+          # an asterisk at the end, determine if the characters up to
+          # but excluding the asterisk are the same
           if ( $exp ne "" && substr($exp, -1, 1) eq "*" ) {
             $exp = substr($exp, 0, length($exp) - 1);
             if ( substr($test_name, 0, length($exp)) ne $exp ) {
+              # no match, try next entry
               next;
             }
+            # if yes, fall through to set the exp-fail status
           } else {
+            # no match, try next entry
             next;
           }
         }

mysql-test/mysql-test-run.pl

@@ -170,6 +170,7 @@ my $config; # The currently running config
 my $current_config_name; # The currently running config file template
 
 our $opt_experimental;
+our $experimental_test_cases;
 
 my $baseport;
 my $opt_build_thread= $ENV{'MTR_BUILD_THREAD'} || "auto";
@@ -963,24 +964,29 @@ sub command_line_setup {
 
   if ( $opt_experimental )
   {
-    if ( open(FILE, "<", $opt_experimental) ) {
+    # read the list of experimental test cases from the file specified on
+    # the command line
+    open(FILE, "<", $opt_experimental) or mtr_error("Can't read experimental file: $opt_experimental");
     mtr_report("Using experimental file: $opt_experimental");
-      $opt_experimental = [];
+    $experimental_test_cases = [];
     while(<FILE>) {
       chomp;
+      # remove comments (# foo) at the beginning of the line, or after a 
+      # blank at the end of the line
       s/( +|^)#.*$//;
+      # remove whitespace
       s/^ +//;              
       s/ +$//;
+      # if nothing left, don't need to remember this line
       if ( $_ eq "" ) {
         next;
       }
+      # remember what is left as the name of another test case that should be
+      # treated as experimental
       print " - $_\n";
-        push @$opt_experimental, $_;
+      push @$experimental_test_cases, $_;
     }
     close FILE;
-    } else {
-      mtr_error("Can't read experimental file: $opt_experimental");      
-    }
   }
 
   foreach my $arg ( @ARGV )