[WWcvs] pg: Improve error messages for unreduced unions.

[dpvc v. a. <we...@ma...>]

Log Message:
-----------
Improve error messages for unreduced unions.

Modified Files:
--------------
    pg/lib/Value:
        AnswerChecker.pm
        Union.pm

Revision Data
-------------
Index: AnswerChecker.pm
===================================================================
RCS file: /webwork/cvs/system/pg/lib/Value/AnswerChecker.pm,v
retrieving revision 1.107
retrieving revision 1.108
diff -Llib/Value/AnswerChecker.pm -Llib/Value/AnswerChecker.pm -u -r1.107 -r1.108
--- lib/Value/AnswerChecker.pm
+++ lib/Value/AnswerChecker.pm
@@ -321,7 +321,8 @@
   my ($result,$error) = $student->isReduced;
   return unless $error;
   return {
-    overlaps => "Your$nth union can be written without overlaps",
+    "overlaps" => "Your$nth union contains overlapping intervals",
+    "overlaps in sets" => "Your$nth union contains sets and intervals that overlap",
     "uncombined intervals" => "Your$nth union can be simplified by combining intervals",
     "uncombined sets" => "Your$nth union can be simplified by combining some sets",
     "repeated elements in set" => "Your$nth union contains sets with repeated elements",
Index: Union.pm
===================================================================
RCS file: /webwork/cvs/system/pg/lib/Value/Union.pm,v
retrieving revision 1.41
retrieving revision 1.42
diff -Llib/Value/Union.pm -Llib/Value/Union.pm -u -r1.41 -r1.42
--- lib/Value/Union.pm
+++ lib/Value/Union.pm
@@ -250,7 +250,7 @@
     if ($x->intersects($y)) {$error = "overlaps"; last}
     if (($x + $y)->reduce->type ne 'Union') {$error = "uncombined intervals"; last}
   }
-  $error = "overlaps" if !$error && $S->intersects($U);
+  $error = "overlaps in sets" if !$error && $S->intersects($U);
   $error = "uncombined sets" if !$error && $Sn > 1 && !$self->getFlag('reduceSets');
   $error = "repeated elements in set" if !$error && !$S->isReduced;
   return $error eq "" unless $error && wantarray;