pnpm add -g not support user's environment path on windows #5283

pnpm version: 7.9.5

Code to reproduce the issue:

1. corepack enable
2. corepack prepare pnpm@7.9.5 --activate
3. corepack setup, it set PNPM_HOME to user's env, and add %PNPM_HOME% to PATH of the user's env.
4. open a new cmd, execute: pnpm add -g @nestjs/cli, error occurs as below:
    ERROR  The configured global bin directory "C:\Users\ilala\AppData\Local\pnpm" is not in PATH
5. add %PNPM_HOME% to PATH of the system env, reexecute: pnpm add -g @nestjs/cli, everything is fine.

Expected behavior:

no error occurs in step4.
corepack setup add PNPM_HOME and PATH to the user's env, pnpm should first check system env, then check user's env, then merge the two to use.

Actual behavior:

user's path is not supported

Additional information:

• node -v prints: v16.17.0
• Windows, macOS, or Linux?: Windows 10 LTSC 2021 x64 21H2 19044.1889