makeindex broken in TL22

[Frank Mittelbach]

Hi folks,

reviewing the index for TLC3 (which is rather large) gave me a small 
heart attack it came out rather scrambled after upgrading to TL22

I gut it down the a reasonable size:

input:

\indexentry {foo}{I-13}
\indexentry {foo}{I-15}
\indexentry {foo}{I-16}
\indexentry {foo}{I-17}
\indexentry {foo}{II-10}
\indexentry {foo}{II-20}

with darwin-universal/makexindex (no options no style no nothing) from 
TL22 I get

   \item foo, II-10, II-20, I-13, I-15--I-17

upmendex does it correctly and so does makeindex in TL21 and TL20, all 
giving

   \item foo, I-13, I-15--I-17, II-10, II-20

as expected

---------

Ulrike confirmed that it is also a problem on windows and with miktex, 
so not a question of MacOS

cheers
frank