Not displaying some lower layers where there are no tiles in the upper imagery layer

[naoliv]

Go to -22.328129695061985, -52.36428678552035 and enable the "IBGE Mapa de Setores Rurais" layer.
At the scale of 5 km we have this:

Black parts are where we don't have tiles available and white parts where we have. Good.

Then enable the Bing layer, with the IBGE layer on top of Bing:

Still good. We are seeing the lower layer where we don't have data in the IBGE one.

Now zoom one level, at the scale of 4 km:

There is a black part where we should be seeing the Bing layer, but we aren't.

At 2 km scale we have even more black areas:

And at 1 km scale:

Shouldn't we keep seeing the Bing layer instead black areas, since there are no tiles there? (the error message is also saying this: "No tile at this zoom level")

JOSM:

Build-Date:2016-10-09 13:51:08
Revision:11110
Is-Local-Build:true

Identification: JOSM/1.5 (11110 SVN pt_BR) Linux Debian GNU/Linux unstable (sid)
Memory Usage: 674 MB / 4029 MB (376 MB allocated, but free)
Java version: 1.8.0_102-8u102-b14.1-2-b14, Oracle Corporation, OpenJDK 64-Bit Server VM
Screen: :0.0 1920x1080
Maximum Screen Size: 1920x1080
Java package: openjdk-8-jre:amd64-8u102-b14.1-2
Java ATK Wrapper package: libatk-wrapper-java:all-0.33.3-9
VM arguments: [-Dawt.useSystemAAFontSettings=on]
Dataset consistency test: No problems found

Plugins:
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+ Create_grid_of_ways (32699)
+ FastDraw (32938)
+ FixAddresses (32796)
+ ImportImagePlugin (32699)
+ OpeningHoursEditor (32699)
+ PicLayer (32796)
+ SimplifyArea (32796)
+ apache-commons (32699)
+ buildings_tools (32944)
+ download_along (32946)
+ editgpx (32699)
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+ kendzi3d (1.0.191)
+ kendzi3d-resources (0.0.1)
+ log4j (32699)
+ measurement (32936)
+ merge-overlap (32699)
+ opendata (32898)
+ pdfimport (32796)
+ photo_geotagging (32699)
+ poly (32699)
+ reverter (32796)
+ tageditor (33021)
+ tagging-preset-tester (32869)
+ todo (30000)
+ turnlanes-tagging (252)
+ turnrestrictions (32796)
+ undelete (32699)
+ utilsplugin2 (32815)

[wiktorn]

Closed in [o33034]