Error during cloning boom

[pranith]

Using master branch and a fresh clone, we get the following error:

$ ./scripts/init-submodules.sh
Submodule 'boom' (https://github.com/ucb-bar/riscv-boom.git) registered for path 'boom'
Submodule 'rocket-chip' (https://github.com/ucb-bar/rocket-chip.git) registered for path 'roc
ket-chip'
Submodule 'torture' (https://github.com/ucb-bar/riscv-torture.git) registered for path 'tortu
re'
Cloning into 'boom'...
remote: Enumerating objects: 9625, done.
remote: Total 9625 (delta 0), reused 0 (delta 0), pack-reused 9625
Receiving objects: 100% (9625/9625), 7.79 MiB | 0 bytes/s, done.
Resolving deltas: 100% (5957/5957), done.
Checking connectivity... done.
fatal: reference is not a tree: d0dad4e3250669fd6ca0ae5e888dbdd4f620d845