Git on Azure self hosted agent pipelines - github

Question

I am building an Azure pipeline for a GitHub web site to run on Windows Self-Hosted agents.
The default branch for the GitHub project is develop, all developers commit to this branch. I want a script that will merge develop to release for the time where a version is on tests and merge release to master once in production.
I'm new with git commands, I know the pipeline runs under a service account on the agent, behind a proxy and the pipeline impersonate somehow to another account to connect to GitHub.
To test my script, I logged onto the server as the service account and ran the following commands:
REM At start, the pipeline is on the develop branch so I move to release branch
C:\Agent\_work\29\s> git checkout release
>Updating files: 100% (928/928), done.
>Previous HEAD position was a62***: *comment*
>Switched to a new branch 'release'
>Branch 'release' set up to track remote branch 'release' from 'origin'.
C:\Agent\_work\29\s>git tag "branchTests"
C:\Agent\_work\29\s>git status
>On branch release
>Your branch is up to date with 'origin/release'.
>
>nothing to commit, working tree clean
REM I understood I had to first get the release branch and then pull the develop branch over it before pushing it all back
C:\Agent\_work\29\s>git pull origin develop
fatal: could not read Username for 'https://github.com': No such file or directory
C:\Agent\_work\29\s>git push --verbose --repo=release --set-upstream release
>Pushing to release
>fatal: 'release' does not appear to be a git repository
>fatal: Could not read from remote repository.
>
>Please make sure you have the correct access rights and the repository exists.
I have two questions:
Is my script correct in that context ?
Can this username error come from that I use the service account ? I should impersonate somehow as the same account the pipeline does ?
Thanks.
########## Update 1
I noticed that I don't need to add this if I don't disable the checkout in the pipeline
git config --global user.email "you#example.com"
git config --global user.name "xxx"
git remote set-url origin https://user:{GitHubPAT}#github.com/xxx/xxx.git
I have two files:
stages:
- stage: InitRelease
jobs:
- job: Branch
steps:
- checkout: self
clean: true
persistCredentials: true
- template: git-branch-source-2-target.yml#templates
parameters:
Tag: '${{ variables.projectName }}_${{ variables.buildId }}'
git-branch-source-2-target.yml
parameters:
- name: 'SourceBranch'
default: 'develop'
type: string
- name: 'TargetBranch'
default: 'release'
type: string
- name: 'Tag'
default: ''
type: string
steps:
- task: CmdLine#2
enabled: true
displayName: 'GIT Release'
inputs:
script: |
git checkout ${{parameters.SourceBranch}}
git pull origin
git checkout ${{parameters.TargetBranch}}
git pull origin
git tag ${{parameters.Tag}}
git push --tags
git merge ${{parameters.SourceBranch}}
git push origin --all --verbose
Thanks !

Answer 1

Run the following command in the cmd task of the pipeline:
git config --global user.email "you#example.com"
git config --global user.name "xxx"
git remote set-url origin https://user:{GitHubPAT}#github.com/xxx/xxx.git
git checkout develop
git pull origin
git checkout release
git merge develop
git push origin --all