Unable to build linux-firmware

Created by: PureTryOut

Right now I'm unable to build linux-firmware (for armhf). pmbootstrap already saw it coming:

WARNING: Option !tracedeps is not set, but we're cross-compiling in the native chroot. This will probably fail!
(native) build armhf/linux-firmware-20180417-r1.apk

And what do you know, it failed!

ERROR: Unable to open root: No such file or directory
ERROR: Failed to open apk database: No such file or directory
>>> ERROR: linux-firmware*: create_apks failed
>>> ERROR: linux-firmware: all failed

This effectively makes it impossible right now to install postmarketOS to a Raspberry Pi (3 in my case).

EDIT: I see this was already mentioned by @yangxuan8282 here.