Auto merge of rust-lang#122321 - majaha:mingw_ci_new, r=Mark-Simulacrum

`mv` tools off the path instead of `rm -r`-ing them in `install-msys2.sh`

This is a follow up patch to rust-lang#121182

r? `@Mark-Simulacrum`

INSTALL.md

@@ -154,11 +154,11 @@ toolchain.
  however this is not recommended as it's excrutiatingly slow, and not frequently
  tested for compatability.
 
-2. Start a MINGW64 or MINGW32 shell (depending on whether you want 32-bit
+3. Start a MINGW64 or MINGW32 shell (depending on whether you want 32-bit
  or 64-bit Rust) either from your start menu, or by running `mingw64.exe`
  or `mingw32.exe` from your MSYS2 installation directory (e.g. `C:\msys64`).
 
-3. From this terminal, install the required tools:
+4. From this terminal, install the required tools:
 
  ```sh
  # Update package mirrors (may be needed if you have a fresh install of MSYS2)
@@ -178,7 +178,7 @@ toolchain.
  mingw-w64-x86_64-ninja
  ```
 
-4. Navigate to Rust's source code (or clone it), then build it:
+5. Navigate to Rust's source code (or clone it), then build it:
 
  ```sh
  python x.py setup dist && python x.py build && python x.py install

src/ci/scripts/install-msys2.sh

@@ -28,16 +28,19 @@ if isWindows; then
  # Install pacboy for easily installing packages
  pacman -S --noconfirm pactoys
 
- # Delete these pre-installed tools so we can't accidentally use them, because we are using the
- # MSYS2 setup action versions instead.
- # Delete pre-installed version of MSYS2
- echo "Cleaning up tools in PATH"
- rm -r "/c/msys64/"
- # Delete Strawberry Perl, which contains a version of mingw
- rm -r "/c/Strawberry/"
- # Delete these other copies of mingw, I don't even know where they come from.
- rm -r "/c/mingw64/"
- rm -r "/c/mingw32/"
+ # Remove these pre-installed tools so we can't accidentally use them, because we are using the
+ # MSYS2 setup action versions instead. Because `rm -r`-ing them is slow, we mv them off path
+ # instead.
+ # Remove pre-installed version of MSYS2
+ echo "Cleaning up existing tools in PATH"
+ notpath="/c/NOT/ON/PATH/"
+ mkdir --parents "$notpath"
+ mv -t "$notpath" "/c/msys64/"
+ # Remove Strawberry Perl, which contains a version of mingw
+ mv -t "$notpath" "/c/Strawberry/"
+ # Remove these other copies of mingw, I don't even know where they come from.
+ mv -t "$notpath" "/c/mingw64/"
+ mv -t "$notpath" "/c/mingw32/"
  echo "Finished cleaning up tools in PATH"
 
  if isKnownToBeMingwBuild; then