As initially reported by Eric Chamberland in

http://www.open-mpi.org/community/lists/users/2013/04/21689.php, the
assert in opal_datatype_is_contiguous_memory_layout() is not always
correct -- he supplied a test case where it was not valid,
essentially:

 1. Call MPI_Type_create_indexed_block(0, ..., &newtype) and commit newtype
 1. Call MPI_Type_create_resized(newtype, 0, nonzero_value, &resized) and commit resized
 1. Call MPI_File_set_view with resized

This will eventually call opal_datatype_is_contiguous_memory_layout(),
and the assert will fail.  After some consultation with George, it was
determined that the assert() is basically good, but it needs to also
check for (count != 0).

This commit was SVN r28398.

opal/datatype/opal_datatype.h

@@ -217,7 +217,7 @@ opal_datatype_is_contiguous_memory_layout( const opal_datatype_t* datatype, int3
 {
     if( !(datatype->flags & OPAL_DATATYPE_FLAG_CONTIGUOUS) ) return 0;
     if( (count == 1) || (datatype->flags & OPAL_DATATYPE_FLAG_NO_GAPS) ) return 1;
-    assert( (OPAL_PTRDIFF_TYPE)datatype->size != (datatype->ub - datatype->lb) );
+    assert( (OPAL_PTRDIFF_TYPE)datatype->size != (datatype->ub - datatype->lb)  && count != 0 );
     return 0;
 }