run provisioned tox in current working directory instead of {tox_root}

running in a different working directory than the parent process changes the
interpretation of relative paths on the command line passed to the provisoned
tox and must be avoided.

fix #2876

docs/changelog/2876.bugfix.rst

@@ -0,0 +1,7 @@
+When executing via the provisioning environment (``.tox`` by default), run
+``tox`` in working directory of the parent process.
+
+Prior to this change (from tox 4.0.0), the provisioned ``tox`` would execute with
+``{tox_root}`` as the working directory, which breaks when a relative path is
+passed to ``-c`` or ``--conf`` and ``tox`` is executed in a working directory
+other than ``{tox_root}`` - by :user:`masenf`.

src/tox/provision.py

@@ -150,5 +150,5 @@ def run_provision(name: str, state: State) -> int:
         raise HandledError(f"cannot provision tox environment {tox_env.conf['env_name']} because {exception}")
     args: list[str] = [str(env_python), "-m", "tox"]
     args.extend(state.args)
-    outcome = tox_env.execute(cmd=args, stdin=StdinSource.user_only(), show=True, run_id="provision")
+    outcome = tox_env.execute(cmd=args, stdin=StdinSource.user_only(), show=True, run_id="provision", cwd=Path.cwd())
     return cast(int, outcome.exit_code)