LineageOS installation fails on pioneer with "adb: failed to stat file"

The LineageOS installation fails on pioneer.

Command:

ait install-unlocked lineageos+opengapps-pico+fdroid H4113

Output:

[...]
adb: failed to stat file lineage-16.0-20190812-nightly-pioneer-signed.zip: No such file or directory

It tries to sideload a non-existing LineageOS image.