[vcpkg-tool] x-add-version --all crashes if there are uncommited ports in the tree.

[Neumann-A]

neumann@heineken MINGW64 /e/vcpkg_folders/master (fortran_flang_ifort_combined)
$ ./vcpkg.exe x-add-version --all --overwrite-version
warning: can't obtain SHA for port vcpkg-tool-sed
-- Did you remember to commit your changes?
***No files were updated***
internal error: D:\a\_work\1\s\src\vcpkg\commands.add-version.cpp(556): vcpkg has crashed; no additional details are available.
Please open an issue at https://github.com/microsoft/vcpkg/issues/new?template=other-type-of-bug-report.md&labels=category:vcpkg-bug with detailed steps to reproduce the problem.

didn't happen with the previous versions.
So either microsoft/vcpkg-tool#489 or microsoft/vcpkg-tool#526 broke it.

cc @vicroms

[LilyWangLL]

I have reproduced this issue locally, if I create a new port, but I uncommit this port and use command ./vcpkg.exe x-add-version --all --overwrite-version, vcpkg will crash and report internal error.

cc @BillyONeal