Github Actions: [remote rejected] master -> master (shallow update not allowed), error: failed to push some refs - github

Question

In my Github workflow, I am checking out two repositories. Subsequently I merge two directories of the workflow repo "repoA" with repo "repoB". When pushing to repoB, I get an error:
From ../repoA
* [new branch] master -> workspace/master
Automatic merge went well; stopped before committing as requested
[master cbd72fe] Update
To https://github.com/username/repoB.git
! [remote rejected] master -> master (shallow update not allowed)
error: failed to push some refs to 'https://username#github.com/username/repoB.git'
##[error]Process completed with exit code 1.
I don't understand why my repo is shallow and how to fix it. The Github workflow file:
name: test
on: [push]
jobs:
build:
runs-on: ubuntu-latest
steps:
- name: Checkout current repo
uses: actions/checkout#v2
with:
path: repoA
- name: Checkout other repo
uses: actions/checkout#v2
with:
repository: username/repoB
path: repoB
token: ${{ secrets.ACCESS_TOKEN }}
- name: Update repo
run: |
cd repoB
git remote add repoa ../repoA
git fetch --unshallow repoa
git config --global user.email "asd#asd.com"
git config --global user.name "username"
git merge -s ours --no-commit --allow-unrelated-histories repoa/master
rm -rf webserver
rm -rf etl
git add .
git read-tree --prefix=webserver -u repoa/master:serv
git read-tree --prefix=etl -u repoa/master:misc_projects/etl
git add .
git commit -m "Update" -a
git push -f https://username#github.com/username/repoB.git

Answer 1

By default actions/checkout only checks out a single commit, making the checkout shallow. If you want all history you can set the fetch-depth input to 0.
See the documentation here.
- uses: actions/checkout#v2
with:
fetch-depth: 0