Vehicle parts retain damage fraction, don't stack, can't be repaired

[Nandorianen]

Game version:
0.C-7181
Operating system:
Win 7 64 bit.
Tiles or curses:
Tiles.
Mods active:
"dda",
"StatsThroughSkills",
"blazemod",
"deoxymod",
"ew_pack",
"no_npc_food",
"no_religious_Texts",
"no_reviving_zombies",
"novitamins"

Expected behavior

Vehicle parts (when not installed) should either be:
a) not damaged, stacking, or
b) damaged, show a damage indicator in inventory, and be repairable.

Actual behavior

Many vehicle parts have small enough damage to not be considered as having a proper damage level. They show up as white in inventory, cannot be repaired (only reinforced), but they do not stack with truly undamaged items. In save file they are shown having something like 0.334000, 0.583333, 0.666667, 0.668000, or 0.833333 damage. Parts that have the exact same amount of damage stack with each other. It looks like there is a piece of code somewhere that tries to damage parts by a proper amount (1, 2, 3) that then gets divided by some number that shouldn't be there.

Steps to reproduce the behavior

Find a naturally-generated vehicle and fully disassemble it. You should get multiple non-stacking white parts. Not sure if you can reproduce this by just driving a brand-new car through random bushes of love.

This was mentioned back in #20871, but for some reason it wasn't considered an issue at the time.

[Leland]

Save file?

[Nandorianen]

Made a fresh character from a fresh install of the 0.C-7214. Walked up to a first car that had three green wheels and one red wheel. Took off the three "undamaged" wheels and got two stacks of items: 2 with no damage, 1 with a fraction.
Also, if I remove the last wheel and repair it, it goes into a third stack with a different fraction of damage.
Here's a save.
save.zip
Here's a relevant part of it.
{ "typeid": "wheel", "invlet": 113, "damage": 0.340000 }, { "typeid": "wheel", "invlet": 115 }, { "typeid": "wheel", "invlet": 115 }

[Nandorianen]

The problem seems to be broader than just vehicle parts generation.

Got to the point where I organize and repair my heaps of items. When I repair vehicle parts with proper damage values (1.0, 2.0, 3.0, etc), I get back parts with damage fractions as above that only stack with other parts damaged by exactly the same amount.

When I repair and refit clothing I get back items with 0 damage, but they won't stack at first.
{ "typeid": "helmet_liner", "invlet": 97, "damage": 0.000000, "item_tags": [ "FIT" ] }, { "typeid": "helmet_liner", "invlet": 104, "damage": 0.000000, "item_tags": [ "FIT" ] }, { "typeid": "helmet_liner", "invlet": 109, "damage": 0.000000, "item_tags": [ "FIT" ] }
They start stacking after I reload my game. This problem does not seem to occur when I refit items without repairing them.

Reinforcing items makes them stack again immediately.
{ "typeid": "helmet_liner", "invlet": 109, "damage": -1.000000, "item_tags": [ "FIT" ] }, { "typeid": "helmet_liner", "invlet": 109, "damage": -1.000000, "item_tags": [ "FIT" ] }, { "typeid": "helmet_liner", "invlet": 109, "damage": -1.000000, "item_tags": [ "FIT" ] }
This works both on clothing and on vehicle parts.

Checked a few backpacks that wouldn't stack after repair. Turned out two of them had their birthday recorded in a save file. They stacked after reloading.
{ "typeid": "backpack", "bday": 676313, "invlet": 113, "damage": 0.000000 }, { "typeid": "backpack", "bday": 676313, "invlet": 113, "damage": 0.000000 }, { "typeid": "backpack", "invlet": 104, "damage": 0.000000 }, { "typeid": "backpack", "invlet": 104, "damage": 0.000000 }