[bootstrapper] Improve handling of invalid hash

Description

I receive a

The file 'C:\Windows\system32\config\systemprofile\AppData\Local\NuGet\Cache\Paket\5.92.3\paket.exe' already exists. 

error when calling “paket.exe restore” having bumped the version to 5.92.3.

Have never seen this before. It goes away on a brand new build agent (they’re automated), but comes back again.

Repro steps

Not yet able to reproduce. Known aspects:

• Occurs when calling paket.exe restore
• Most branches on build server running on 5.85.1 with paket.exe in magic mode, with version passed as argument.
• New branch on build server running 5.92.3 with paket.exe in magic mode, with version passed in paket.dependencies.
• Build servers rebuilt from scratch each day, and happened two days running so far.
• Works successfully on first run of the day.
• Subsequent builds of branch fail on that build server. Not sure if there is interaction with other builds going on here.
• Happened once on local machine but haven’t been able to reproduce since after clearing cache folder.

Expected behavior

paket.exe restores packages as in previous versions.

Actual behavior

The file ‘C:\Windows\system32\config\systemprofile\AppData\Local\NuGet\Cache\Paket\5.92.3\paket.exe’ already exists.

Packages are then not restored.

Known workarounds

Kill the build server and force a fresh instance.

[matthid]

I don’t even know what we changed there recently, could that be a side effect from signing the .exe?

[matthid]

So the immediate problem has been solved #2729 and the hashes match again, please retry. I’ll leave this open as the bootstrapper still needs to be fixed in case this happens again. A PR is appreciated.