I noticed this in the course of Endless OS removing Python 2.7 entirely. We don't ship /usr/lib/adobe-flashplugin/manifest.json, and I couldn't find a copy to fully verify this patch, but I tested with a non-ASCII JSON file (the obvious way that 2.7 -> 3.x would break) and it seems to work fine.
I noticed this in the course of Endless OS removing Python 2.7 entirely. We don't ship /usr/lib/ adobe-flashplug in/manifest. json, and I couldn't find a copy to fully verify this patch, but I tested with a non-ASCII JSON file (the obvious way that 2.7 -> 3.x would break) and it seems to work fine.