Defined alternate tools should be skipped by the Install/Update Tools command

[jlucktay]

Is your feature request related to a problem? Please describe.
If an alternate location for a tool is already defined (e.g. "go.alternateTools": { "gometalinter": "/usr/local/bin/golangci-lint" }) the Install/Update Tools command will still install the same command at another location.

Describe the solution you'd like
When such an alternate definition is already in place for any tool, Install/Update Tools should skip said tool.

Additional context
In my own circumstance, I also have "go.toolsGopath": "~/vscode-go" set, to reduce clutter by keeping VSCode's tools out of my ~/go/bin directory.

[ramya-rao-a]

Fair point, PRs are most welcome to make this change to have the Go: Install/Update Tools command skip such tools.

Code Pointers:

• Set up local dev env for the extension
• https://github.com/microsoft/vscode-go/blob/0.13.0/src/goInstallTools.ts#L60 is where we show the drop down with all the tools

[ramya-rao-a]

This should be fixed in the latest version (0.13.1) of the extension.

Thanks for reporting @jlucktay!