make sure only the full path is grabbed

Author: dothebart

release_tester/arangodb/instance.py

@@ -268,8 +268,10 @@ def launch_manual_from_instance_control_file(
         """launch instance without starter with additional arguments"""
         self.load_starter_instance_control_file()
         command = [str(sbin_dir / self.instance_string)] + self.instance_arguments[1:] + moreargs
-        dos_old_install_prefix_fwd = str(old_install_prefix).replace("\\", "/")
-        dos_new_install_prefix_fwd = str(new_install_prefix).replace("\\", "/")
+        old_install_prefix = old_install_prefix + os.sep
+        new_install_prefix = new_install_prefix + os.sep
+        dos_old_install_prefix_fwd = old_install_prefix.replace("\\", "/")
+        dos_new_install_prefix_fwd = new_install_prefix.replace("\\", "/")
 
         is_cache_supported = is_column_cache_supported(current_version) and enterprise
         # in 'command' list arguments and values are splitted

release_tester/arangodb/starter/manager.py

@@ -708,8 +708,8 @@ def manually_launch_instances(self, which_instances, moreargs, waitpid=True, kil
                         instance.kill_instance()
                     instance.launch_manual_from_instance_control_file(
                         self.cfg.sbin_dir,
-                        self.old_install_prefix,
-                        self.cfg.install_prefix,
+                        str(self.old_install_prefix),
+                        str(self.cfg.install_prefix),
                         self.cfg.version,
                         self.enterprise,
                         moreargs,