Installing old package versions from the manifest git history

[leumasme]

From what I can find, when installing a specific package version that is different from the current manifest version, scoop just tries to generate the manifest based on the auto-update configuration of the manifest

Scoop/libexec/scoop-download.ps1

Lines 62 to 70 in f930280

	# Generate manifest if there is different version in manifest
	if (($null -ne $version) -and ($manifest.version -ne $version)) {
	$generated = generate_user_manifest $app $bucket $version
	if ($null -eq $generated) {
	error 'Manifest cannot be generated with provided version'
	continue
	}
	$manifest = parse_json($generated)
	}

Scoop/lib/manifest.ps1

Lines 132 to 154 in f930280

	function generate_user_manifest($app, $bucket, $version) {
	# 'autoupdate.ps1' 'buckets.ps1' 'manifest.ps1'
	$app, $manifest, $bucket, $null = Get-Manifest "$bucket/$app"
	if ("$($manifest.version)" -eq "$version") {
	return manifest_path $app $bucket
	}
	warn "Given version ($version) does not match manifest ($($manifest.version))"
	warn "Attempting to generate manifest for '$app' ($version)"
	if (!($manifest.autoupdate)) {
	abort "'$app' does not have autoupdate capability`r`ncouldn't find manifest for '$app@$version'"
	}
	ensure (usermanifestsdir) | out-null
	try {
	Invoke-AutoUpdate $app "$(Convert-Path (usermanifestsdir))\$app.json" $manifest $version $(@{ })
	return Convert-Path (usermanifest $app)
	} catch {
	write-host -f darkred "Could not install $app@$version"
	}
	return $null
	}

Considering that scoop buckets are a git repository anyway, why doesn't scoop first try to search the git history of the manifest file for the specified version?
This of course won't work in various scenarios, such as the version being older than it's scoop manifest, but the current approach also does not work in a lot of cases (often old downloads are linked on from a separate page, or the downloads history is paginated, ...). In case of failure, scoop could simply fall back to the current approach of generating the manifest.

[rashil2000]

Tracked here: #3894