When used with 4 digit port numbers or with the fixed 5 digit emulator images the emulator registers as emulator-%d instead of using the localhost:%d variant. I don't remember the exact details now but the list device shows it as being emulator-%d.

I have a feeling that something stops working if the localhost:%d variant is still used. It is probably related to the fact that the two connections are treated as being distinct and if registered as localhost:%d the latter doesn't work.

On a side note I haven't tested the fix that the Android guys made to the 5 digit port number code. That may just break existing android-emulator-plugin instances when it is deployed due to the emulator vs localhost issue. My fix here which uses 3 consecutive 4 digit port numbers should be safe in old/new variants.

I haven't looked at the Android bug 19913 so can't comment on that.