Conda activation problem on ptvsd 5.x

[huguesv]

Describe the bug
Conda activation doesn't work with ptvsd 5.x (but works when debugging with 3.x or when launching without debugging). This is using VS 2019 dogfood build 16.5 Preview 3.

Steps to Reproduce
Easiest way to demonstrate is to check if numpy loads successfully in a conda env.

1. Create a new python app
2. Create a conda environment and install python=3.7 numpy
3. Debug (F5) this code

import numpy
print(numpy.__version__)

Expected behavior
Runs without error

Additional context and screenshots

Loaded 'numpy.core'
Loaded 'numpy'
Loaded '__main__'
Loaded 'runpy'
Traceback (most recent call last):
  File "C:\Users\huvalo\.conda\envs\condaenv23b\lib\site-packages\numpy\core\__init__.py", line 24, in <module>
    from . import multiarray
  File "C:\Users\huvalo\.conda\envs\condaenv23b\lib\site-packages\numpy\core\multiarray.py", line 14, in <module>
    from . import overrides
  File "C:\Users\huvalo\.conda\envs\condaenv23b\lib\site-packages\numpy\core\overrides.py", line 7, in <module>
    from numpy.core._multiarray_umath import (
ImportError: DLL load failed: The specified module could not be found.

[huguesv]

ptvsd.launcher-10228.log
ptvsd.server-11724.log
ptvsd.adapter-10092.log

One thing that is suspicious is that the launcher logs show that the environment variables used by the adapter to launch the program have both a PATH entry and a Path entry.

[int19h]

Yeah, it does treat environment variable names as case-sensitive (which they are on Unix), so "Path" and "PATH" end up separate. We should do case normalization for "env" keys in the adapter on Windows.

Is there any particular reason why it's "Path", by the way? The canonical name is uppercase. If we control the code that creates that var, this should probably be fixed. Or does it come from the conda activation script?

[huguesv]

It comes back as "PATH" from the conda activation script in Python.
It comes back as "Path" when calling System.Environment.GetEnvironmentVariables() in C#.
Eventually we merge them using a case-insensitive dictionary and we end up with "Path".

[int19h]

Fixed.