Replacing Chunks from Backup fails to find correct region file

[DaChrissi]

I was using your awesome tool to fix a world which got broken during it's upgrade to 1.13, however I had some issues getting it to replace chunks from a backup:
When trying to replace a chunk I get the following message:

The region file doesn't exist in the backup directory: ..\..\Workspace\Backup\region/r.-6.6875.4.9375.mca

Environment:

OS: Windows 10
Python: 3.7.4
regionfixer: 0.3.1

Steps to reproduce:

Create a new world in minecraft and create a copy of it, which will simulate a Backup. Using NBT Explorer, corrupt a chunk. In this example, I changed PosX and PosY, to create a wrong located chunk. I modified chunk -16/-16, which is located in r.-1.-1.mca at offset 16/16.

A scan reveals the broken chunk correctly:

Chunk problems:
----------------------------------
| Problem | Wrong located  Total |
----------------------------------
|  Count  |       1         782  |
----------------------------------

trying to replace the chunk however produces an error:

python regionfixer.py --replace-wrong-located --backup ..\..\Workspace\Dummy_Backup\ ..\..\Workspace\Dummy\

####### Replacing chunks with status: Wrong located ########

------ New chunk to replace. Coords: x = -16; z = -16 ------
The region file doesn't exist in the backup directory: ..\..\Workspace\Dummy_Backup\region/r.-0.5.-0.5.mca

0 replaced of a total of 1 chunks with status: Wrong located

Proposed Solution:

The program is trying to access the region file r.-0.5.-0.5.mca instead of r.-1.-1.mca.
It's using floating point numbers instead of integers while converting from chunk coordinates to region coordinates, so chunk -16/-16 becomes region -0.5/-0.5, when it should be -1/-1.

Replace single slashes with double slashes on lines 1387 and 1388 in regionfixer_core/world.py to force integer division:

def get_chunk_region(chunkX, chunkZ):
    """ Returns the name of the region file given global chunk
        coords """

    regionX = chunkX // 32
    regionZ = chunkZ // 32

    region_name = 'r.' + str(regionX) + '.' + str(regionZ) + '.mca'

    return region_name

In my original error message, it should access the region file at 6 / 4 instead of at 6.6875 / 4.9375.
After modifying world.py this way, the error disappeared and all broken chunks were correctly replaced from the backup.

[Fenixin]

Hello!

Thank you very much for you thorough bug report and solution. This is already in the branch fixes and it will be in master when I do some reviews int he issues.

I'm closing this, feel free to reopen if there is anything you want to add.

Again, thanks!