This causes problems when the two drivers fall out of sync, for example, I was not able to compile the stdlib with the new swift driver natively on Android when I tried it last month with the Oct. 21 trunk source snapshot.
Turns out out-of-sync drivers was not the issue, instead it was the issue that Artem was trying to fix in my second link, that a symlinked swift-driver then tries to build with the prebuilt Swift toolchain and not the one you are freshly building. I had run into this issue months earlier on linux, but didn't connect it to this instance on Android because the errors were different. Simply copying over swift-driver manually instead fixed it, and that's what Artem's merged pull already did in trunk a couple days after the Oct. 21 tag I built, so this is fixed now.