The prepare-pipeline script should setup the vcpkg queue time variables for new package pipelines that get created

[ahsonkhan]

One issue we hit when releasing a package for the first time using the created pipeline, such as the EventHubs package, is that the two required queue time variables don't exist:

• VcpkgForkBranchName
• VcpkgPRTitle

Without these defined, the last publish to vcpkg step fails when triggering the release. Note these variables don't require to have a value set to them, just that they exist in the pipeline definition.

See
https://dev.azure.com/azure-sdk/internal/_build/results?buildId=2988130&view=logs&j=89ce207c-d97b-5c1d-20a4-270af1e71c5e&t=2d515f10-b48d-5a92-77dd-16c373a6ba1f

2023-08-09T00:31:14.5434633Z ##[section]Starting: Push changes
2023-08-09T00:31:14.5519729Z ==============================================================================
2023-08-09T00:31:14.5520185Z Task         : PowerShell
2023-08-09T00:31:14.5520422Z Description  : Run a PowerShell script on Linux, macOS, or Windows
2023-08-09T00:31:14.5520681Z Version      : 2.220.0
2023-08-09T00:31:14.5520895Z Author       : Microsoft Corporation
2023-08-09T00:31:14.5521108Z Help         : https://docs.microsoft.com/azure/devops/pipelines/tasks/utility/powershell
2023-08-09T00:31:14.5521359Z ==============================================================================
2023-08-09T00:31:15.3800311Z Generating script.
2023-08-09T00:31:15.3842080Z Formatted command: . 'D:\a\_work\1\s\eng\common\scripts\git-branch-push.ps1' -PRBranchName "$(VcpkgForkBranchName)" -CommitMsg "not-specified" -GitUrl "https://***@github.com/azure-sdk/vcpkg.git" -PushArgs "" -SkipCommit $true
2023-08-09T00:31:15.4143524Z ========================== Starting Command Output ===========================
2023-08-09T00:31:15.4315395Z ##[command]"C:\Program Files\PowerShell\7\pwsh.exe" -NoLogo -NoProfile -NonInteractive -ExecutionPolicy Unrestricted -Command ". 'D:\a\_work\_temp\d4265d54-6cdc-4764-b5a9-27618572fedf.ps1'"
2023-08-09T00:31:17.6926081Z VcpkgForkBranchName : �[31;1mThe term 'VcpkgForkBranchName' is not recognized as a name of a cmdlet, function, script file, or executable program.
2023-08-09T00:31:17.6927287Z Check the spelling of the name, or if a path was included, verify that the path is correct and try again.
2023-08-09T00:31:17.6928248Z At D:\a\_work\_temp\d4265d54-6cdc-4764-b5a9-27618572fedf.ps1:4 char:76
2023-08-09T00:31:17.6929655Z + … pts\git-branch-push.ps1' -PRBranchName "$(VcpkgForkBranchName)" -Comm …
2023-08-09T00:31:17.6930518Z +                                             ~~~~~~~~~~~~~~~~~~~
2023-08-09T00:31:17.6931166Z + CategoryInfo          : ObjectNotFound: (VcpkgForkBranchName:String) [], ParentContainsErrorRecordException
2023-08-09T00:31:17.6931791Z + FullyQualifiedErrorId : CommandNotFoundException�[0m
2023-08-09T00:31:17.8773857Z ##[error]PowerShell exited with code '1'.
2023-08-09T00:31:17.9050015Z ##[section]Finishing: Push changes

From @danieljurek:

we should either be creating those variables in the prepare-pipelines script or (more likely) handling the scenario where those variables don't exist in the pipeline definition so this kind of error doesn't happen again

[LarryOsterman]

Addition: The release pipeline should be resilient in the face of these variables being absent.