As discussed on IRC, linux-firmware is intentionally not installed due to being a .deb, but nic-firmware and scsi-firmware (which are .udebs) are.
The particular issue at hand here has been fixed in the linux-firmware source package (bug 944108). If you encounter further problems with files in linux-firmware not being available during installation, please file them against linux-firmware rather than against the installer.
As discussed on IRC, linux-firmware is intentionally not installed due to being a .deb, but nic-firmware and scsi-firmware (which are .udebs) are.
The particular issue at hand here has been fixed in the linux-firmware source package (bug 944108). If you encounter further problems with files in linux-firmware not being available during installation, please file them against linux-firmware rather than against the installer.