[vcpkg_from_git] Unshallow when fetching FETCH_REF

[touraill-adobe]

Fixes #49281.

[touraill-adobe]

@microsoft-github-policy-service agree company="Adobe"

[touraill-adobe]

@vicroms Thanks for grooming this PR! I'm confused by the CI failures, are they happening because my change impacts most cmake ports so they are all rebuilt, but some of them are in fact already broken regardless of my modification? If so, should those issues be fixed in a separate PR and mine rebased on top of it?

[vicroms]

aeron and dpdk had recent updates that built successfully in their own PRs but have issues in the full "all packages" CI, this can sometimes affect PRs such as this one.

[vicroms]

Depends on #49284

[dg0yt]

Depends on #49284

That PR is merged now. This PR needs to be marked ready-for-review.

[vicroms]

More baseline issues, I'll make a new PR to fix them

Now waiting for #49559

[vicroms]

Fixed in upstream

[dg0yt]

Note #49788 (comment):

fatal: --unshallow on a complete repository does not make sense

[BillyONeal]

Should we revert this then?

[touraill-adobe]

Arf sorry about that, it didn't occur to me that git could disallow that and I didn't stumble upon the issue when testing 😞. I suppose a solution could be to check if the repository is shallow beforehand (e.g. with git rev-parse --is-shallow-repository).

[BillyONeal]

To bring this back I think it should have that and also be some form of opt-in