[Bug] r.mapcalc.tiled creates no-data rows at tile borders, when using default patch_backend option

[linakrisztian]

Name of the addon
r.mapcalc.tiled

Describe the bug
When using r.mapcalc.tiled with the default patch option patch_backend="RasterRow" rows of no-data occur at tile borders.
When using patch_backend="r.patch" non of these no-data rows occur.

To Reproduce
Steps to reproduce the behavior:

1. create GRASS location with EPSG:25832
2. import provided test data: r.import input=/path/to/testmap_zeros.tif output=testmap_zeros
3. set region: g.region raster=testmap_zeros
4. use r.mapcalc.tiled with default patch option: r.mapcalc.tiled expression="patch_RasterRow=testmap_zeros+1" nprocs=10 patch_backend="RasterRow"
5. for comparison: use r.mapcalc.tiled with r.patch option: r.mapcalc.tiled expression="patch_rpatch=testmap_zeros+1" nprocs=10 patch_backend="r.patch"
6. zoom to & check tile borders: patch_RasterRow include data-gap rows at tile borders; patch_rpatch does not include data-gap rows at tile borders

Expected behavior
Default patch option should not create no-data rows at tile borders

Screenshots


On the screenshots, you can see a zoomed section of the maps produced in step 4. and 5. The map created with default patch option (patch_RasterRow) contains the no-data rows.

System description (please complete the following information):

• Operating System: Linux Mint 20.3 Cinnamon
• GRASS GIS version: GRASS 8.3.dev

Additional context
grass_example.zip

[petrasovaa]

This is a problem in GridModule, specifically it seems some kind of floating point issue related to computing row number from north:
https://github.com/OSGeo/grass/blob/main/python/grass/pygrass/utils.py#L194