Lock VCPKG_BASE_VERSION in the first job for use in subsequent jobs.

[BillyONeal]

The "2022-02-01" release is broken because the CE build thought the date was 2022-01-31, while the vcpkg.exe build thought it was 2022-02-01. See https://devdiv.visualstudio.com/DefaultCollection/DevDiv/_build/results?buildId=5694458&view=results

The pipeline.startTime variable appears to be reevaluated each time a job starts, and refers to the job start time, not the overall pipeline start time, so when a build crosses 4PM pacific time it produced broken output.

This change gets the first arch_independent stage to write the value it used, and this is fed into the remaining stages.

[BillyONeal]

I didn't let the pipeline this is attached to run to completion because it would have tried to create a GitHub release we don't want, but I did ensure the version is passed into downstream stages before submitting this: https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=5729233&view=results

[strega-nil-ms]

@BillyONeal I see that VCPKG_INITIAL_BASE_VERSION is set to 2022-01-01; is that correct here?

[BillyONeal]

@BillyONeal I see that VCPKG_INITIAL_BASE_VERSION is set to 2022-01-01; is that correct here?

Yes I used the "override" button in that test; I wanted something that would be clearly bogus if it accidentally ran to completion. It needs to look like a date to pass some of our validity checks.

[strega-nil-ms]

@BillyONeal can you try it without doing the override? I want to see those results as well, just to make sure. I believe that if the pipeline runs to completion it only creates a draft release, anyways, that no one outside the team can see

[BillyONeal]

@BillyONeal can you try it without doing the override? I want to see those results as well, just to make sure. I believe that if the pipeline runs to completion it only creates a draft release, anyways, that no one outside the team can see

Unfortunately manually triggering a build requires setting an overriding value.