Convert script and directory _nsis.py subcommands into NSIS code

[marcoesters]

Description

Convert simple script and directory subcommands into NSIS code to further decouple the python dependency from EXE installers (#549). Scripts are already executed directly via cmd.exe for pre-install scripts and mkdirs is a simple directory creation command.

Note that this means that post-install and pre-uninstall script failures will cause the installation/uninstallation process to fail now. I think this is good behavior as it has masked issues in the past (see #942 and #1020).

Checklist - did you ...

• Add a file to the news directory (using the template) for the next release's release notes?
• Add / update necessary tests?
• Add / update outdated documentation?

[lrandersson]

@marcoesters Is this something that is awaiting review? Let me know and I can review it.

[marcoesters]

@marcoesters Is this something that is awaiting review? Let me know and I can review it.

You are free to leave comments, but in the end, I need approval from a constructor maintainer.

[lrandersson]

Why is this no longer needed?

[marcoesters]

It was actually never needed. The uninstallation via conda-standalone already performs the same function during the installation process. I included that line back then by mistake.

[lrandersson]

I see, thanks!

[jaimergp]

Nice cleanups! Thanks!

[marcoesters]

I found a way to remove the rmreg command with uninstallers that don't use conda-standalone. I think this should be part of this PR.

[marcoesters]

Using conda init --reverse instead of rmreg would potentially solve:

• Windows uninstaller might still leave a broken AutoRun registry entry #572
• Investigate the usage of conda init --reverse in uninstallers #588

[lrandersson]

Optional:
In the Function un.onInit we also have this logic:

    ${If} ${FileExists} "$INSTDIR\.nonadmin"
        SetShellVarContext Current
    ${Else}
        SetShellVarContext All
    ${EndIf}

If you prefer, you can create a new variable (maybe un.IsUserInstall?) and assign that variable within that function, to reduce the number of if .nonadmin exists.

I have no strong opinion though, I also like the simplicity with simply using $R0 as in your commit.

[jaimergp]

Suggested change

	push '"$CMD_EXE" /D /C "$INSTDIR\condabin\conda.bat" init cmd.exe --reverse --$R0'
	push '"$CMD_EXE" /D /C "$INSTDIR\condabin\conda.bat" init --reverse --$R0'

Should we revert for both cmd and powershell (which is achieved by passing no positional arguments)?

[marcoesters]

The powershell function does not perform path validation, so it will also revert profiles that point to a different installation. The cmd.exe function, on the other hand, only reverts the autorun entry that belongs to the installation.