panelsetup() fails when id column is not sorted

[daniel klein]

The title is self-explanatory; Here is an example

version 15

clear mata

mata :

// data matrix
X = runiform(10, 3)

// identifier; not sorted
id1 = J(2, 1, (1::5))

// identifier; sorted
id2 = sort(id1, 1)

// info for id1; unexpected
info1 = panelsetup((id1, X), 1)
info1

// info for id2; expected
info2 = panelsetup((id2, X), 1)
info2

end

The output

. clear mata

. 
. mata :
------------------------------------------------- mata (type end to exit) ------------------------------------------------------------------------------------------------------------------------------------------------------
: 
: // data matrix
: X = runiform(10, 3)

: 
: // identifier; not sorted
: id1 = J(2, 1, (1::5))

: 
: // identifier; sorted
: id2 = sort(id1, 1)

: 
: // info for id1; unexpected
: info1 = panelsetup((id1, X), 1)

: info1
         1    2
     +-----------+
   1 |   1    1  |
   2 |   2    2  |
   3 |   3    3  |
   4 |   4    4  |
   5 |   5    5  |
   6 |   6    6  |
   7 |   7    7  |
   8 |   8    8  |
   9 |   9    9  |
  10 |  10   10  |
     +-----------+

: 
: // info for id2; expected
: info2 = panelsetup((id2, X), 1)

: info2
        1    2
    +-----------+
  1 |   1    2  |
  2 |   3    4  |
  3 |   5    6  |
  4 |   7    8  |
  5 |   9   10  |
    +-----------+

: 
: end
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

. 
end of do-file

I do not expect this from the documentation and I find it highly irritating. Any thoughts?

Best
Daniel