Preserve nodata value during saving as a COG

[drnextgis]

No description provided.

[codecov-io]

Codecov Report

Merging #266 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master     #266   +/-   ##
=======================================
  Coverage   90.81%   90.81%           
=======================================
  Files          38       38           
  Lines        5900     5900           
=======================================
  Hits         5358     5358           
  Misses        542      542

Impacted Files	Coverage Δ
telluric/georaster.py	93.44% <0%> (ø)	⬆️

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[arielze]

@drnextgis please refer to this commit which changed the behavior of save_cloud_optimized, in cog files we don't preserve the nodata value, and instead create a mask_array.
b587665

please take a look how this change, influences save method, and in particular the creation of the mask_array, starting from this line:

telluric/telluric/georaster.py

Line 919 in 99a5955

nodata_mask = all([rasterio.enums.MaskFlags.nodata in flags for flags in self.mask_flags])

it should influence rasters that are not in memory (where the image data is not loaded), and pay particular attention to line #919.