Cannot get Halium source

[Leppa]

I'm following the halium porting guide in here, but

repo sync -c -j 16

after

repo init -u https://github.com/Halium/android -b halium-7.1 --depth=1

always fails with

error: Exited sync due to fetch errors

The error

error: RPC failed; curl 56 GnuTLS recv error (-9): Error decoding the received TLS packet.
fatal: the remote end hung up unexpectedly
fatal: early EOF
fatal: index-pack failed

appears repeatedly throughout the log (full log here). Searching this gives me nothing, apart from running

git config --global http.postBuffer 1048576000
git config --global https.postBuffer 1048576000

which has no effect (and seems to be for a different error "error: RPC failed; curl 56 GnuTLS recv error (-9): A TLS packet with unexpected length was received."). Running with -f doesn't fix anything; it doesn't end with error: Exited sync due to fetch errors, but repos are still missing.

I have tried changing revisions to fix this, but that also doesn't fix the issue (I've left LineageOS/android_development on branch lineage-16.0, which seems to fix that repo. I'll be Tring to use lineageOS 16.0 sources to port anyways, so I may need to change the other LOS repos too).