sq: fix upgrade test - use adjusted path

upgrade plugin sets it to `testdir` but in `discover.go()` it gets
changed to `'.'`. This git_root/fmf_root change doesn't happen in
`do_the_discovery`

tmt/steps/discover/fmf.py

@@ -470,11 +470,13 @@ def assert_git_url(plan_name: Optional[str] = None) -> None:
                 raise tmt.utils.DiscoverError(
                     "Failed to process 'dist-git-source'.") from error
         # Discover tests
-        self.do_the_discovery()
+        self.do_the_discovery(path)
 
-    def do_the_discovery(self) -> None:
+    def do_the_discovery(self, path: Optional[Path] = None) -> None:
         """ Discover the tests """
-        path = Path(cast(str, self.get('path'))) if self.get('path') else None
+        # Original path might adjusted already in go()
+        if path is None:
+            path = Path(cast(str, self.get('path'))) if self.get('path') else None
         prune = self.get('prune')
         # Adjust path and optionally show
         if path is None or path.resolve() == Path.cwd().resolve():