I found some more English patch notes and I think they answer this conclusively. Suicide (eg, with Manastone) didn't give you xp loss until the October 20th 1999 patch:
Quote:
General Enhancements
* If a user is killed due to self-inflicted spell or melee damage, experience will be lost.
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http://web.archive.org/web/200102100...et/patches.htm
I would bet that the way the code worked was, if it was an xp death, you got your mana back. This was then changed later on (as described above) because people started exploiting it.