Windows PowerShell correctly inherits environment variables from the environment -- although it may add paths to these variables, it doesn't ignore the existing environment.

PowerShell Core sets the PSModulePath -- completely ignoring and overwriting the existing environment, including the default values set in the Windows System Properties control panel...

This makes PowerShell Core's PSModulepath basically impossible to manage, since it can only be set reliably in a machine profile script --which depend on the install location of the shell, which changes with each release!!

Steps to reproduce

From Windows PowerShell run:

$Env:PSModulePath
pwsh -noprofile -command { $Env:PSModulePath }
pwsh -noprofile -command { powershell -noprofile -command { $Env:PSModulePath } }

From pwsh run:

$Env:PSModulePath
PowerShell -noprofile -command { $Env:PSModulePath }

Expected behavior

pwsh should respect it's environment.

Actual behavior

pwsh overwrites it's environment

Environment data

> $PSVersionTable
Name                           Value
----                           -----
PSVersion                      6.0.2
PSEdition                      Core
GitCommitId                    v6.0.2
OS                             Microsoft Windows 10.0.17134
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0