[Waiting for upstream] Revert pinning Miniconda3-4.5.4 (Python 3.6) on Windows

[tkf]

This if block I introduced in #124 should be removed once conda can install Python 3.7 packages on Windows properly from Anaconda's default channel:

Conda.jl/src/Conda.jl

Lines 131 to 137 in 7094e2a

	if MINICONDA_VERSION == "3"
	# Quick fix for:
	# * https://github.com/JuliaLang/IJulia.jl/issues/739
	# * https://github.com/ContinuumIO/anaconda-issues/issues/10082
	# * https://github.com/conda/conda/issues/7789
	res = "https://repo.continuum.io/miniconda/Miniconda$(MINICONDA_VERSION)-4.5.4-"
	end

Also, this line should be changed to Conda.add("python", env):

Conda.jl/test/runtests.jl

Line 17 in 7094e2a

Conda.add("python=3.6", env) # 3.7 doesn't work on Windows at the moment

@tkelman Do you know where is the upstream issue we should watch? Is it conda/conda#7789?

[tkelman]

This isn't an upstream bug any more, it's a behavior change that they're no longer adding to path. Conda.jl needs to activate environments before trying to use things from them.

[tkf]

Is it possible to activate an environment within a process already running? I think PyCall.jl needs to do that (JuliaPy/PyCall.jl#556 (comment)). Is there equivalent of activate_this.py (of virtualenv) in conda?

[tkf]

conda doens't have activate_this.py: conda/conda#2411

[tkf]

I think there are two problems:

1. conda install ... etc. does not work without activation. This would be easy to solve once conda run returns (resolve #2682 add conda run experimental support conda/conda#7320; presumably, we can just do conda run conda install ...). Unfortunately, it seems Windows support was not added by resolve #2682 add conda run experimental support conda/conda#7320.

2. PyCall.jl can't import Python packages depending on shared libraries. This probably means we have to modify $PATH at PyCall.__init__()...? Does it even work?

I don't have Windows machine to easily explore the solutions for them so probably I shouldn't have started poking around this problem :)

[stevengj]

1. For running conda, I think it is fine to modify the PATH.

2. This is only a problem on Windows, right? PyCall configured with Conda.jl (PyCall.conda == true) could call SetDllDirectory or AddDllDirectory on Windows to modify the DLL search path at runtime.

[tkf]

This is only a problem on Windows, right?

Yes, I think so. For *nix, looking at conda shell.posix activate ... output, it only modifies PATH (not LD_LIBRARY_PATH etc.). So using AddDllDirectory in Windows sounds like a good solution.

I just looked at how conda activate command is implemented. I think we just need to add those paths:

            yield prefix.rstrip("\\")
            yield join(prefix, 'Library', 'mingw-w64', 'bin')
            yield join(prefix, 'Library', 'usr', 'bin')
            yield join(prefix, 'Library', 'bin')
            yield join(prefix, 'Scripts')
            yield join(prefix, 'bin')

--- https://github.com/conda/conda/blob/4.6.0b0/conda/activate.py#L399-L404

[tkf]

It looks like #170 fixed this issue. Closing...