Okay, this is a rather strange ticket.
Everytime I want to try a full playtest, from start to the end, my saved game 
present some weird bug.

It's never the same, it cannot be reproduced, but it still happen. I also saw a 
certain number of reports of crazy bugs, which we couldn't find a source for 
it, but had something in common: Saved game.

Because this must be the third test I am interrupting because my savegame was 
corrupted/unusable/you-get-it, I open this ticket.

This is the same in ticket nature as Unreliable Events - The functions which 
handle them should be first checked, and then fixed if a bug was found (if no 
bug was found, no exploit and etc., the ticket can be disregarded for a while)

Attach your corrupted savegames, please (.shp, .sav.gz), if you want someone to
find what saved data is corrupted.

I think this is a lost cause but attaching one of the bugged savefiles. This one
presents a bug at inventory. Some NPCs in town may also be bugged although I
probably replaced most of them (and deleted one third of the town on the process
because unknown slowdowns at town)

Please apply the "playtest.diff" patch provided or you may find other unrelated
bugs. (I think it is unlikely anything on the diff is related to this bug
though. They mostly adds a new skill, introduce some core resources, rewrites
Butch, and includes Act 2.)

This is the second time such bug happens. Ubuntu MATE 16.04 LTS, 64 bits
notebook. (In case you fail to reproduce)

On side note, it may be due items numeric ID changing for whatever reason.
(Which also fits in “Unreliable savegame”, btw. I did not said “Unreliable
saveing” in case I wasn't clear what this ticket is about: I mean problems after
the game was saved.)

Adding a new item in the middle of the item_specs.lua file will indeed create
some strange bugs, before commit 30db00020.

Given than the reported bug is related to such introduction of new items, this
was then fixed by that commit.