providers: set HOME environment variable using posix format (canonica…

…l#3135)

Windows was interpreting HOME as \root which caused various failures.
When reading home, make sure we use the posix-formatted string.

Signed-off-by: Chris Patterson <chris.patterson@canonical.com>
Co-authored-by: Sergio Schvezov <sergio.schvezov@canonical.com>

snapcraft/internal/build_providers/_base_provider.py

@@ -475,7 +475,7 @@ def _get_env_command(self) -> Sequence[str]:
         )
 
         # Set the HOME directory.
-        env_list.append(f"HOME={self._get_home_directory()}")
+        env_list.append(f"HOME={self._get_home_directory().as_posix()}")
 
         # Configure SNAPCRAFT_HAS_TTY.
         has_tty = str(sys.stdout.isatty())