Updating comment.

Change-Id: I61114423e394561e6838e8ab262f0045892ac2c5

IO/vtkSTLReader.cxx

@@ -442,6 +442,8 @@ int vtkSTLReader::ReadASCIISTL(FILE *fp, vtkPoints *newPts,
         {
         if (!fgets(line, 255, fp))
           {
+          // if fgets() returns an error, it may be due to the fact that the EOF
+          // is reached (BUG #13101) hence we test again.
           done = feof(fp);
           if (!done)
             {