Crash when using meson on existing build generated by older version

[DaanDeMeyer]

Describe the bug

Traceback (most recent call last):
  File "/usr/lib/python3.8/site-packages/mesonbuild/mesonmain.py", line 131, in run
    return options.run_func(options)
  File "/usr/lib/python3.8/site-packages/mesonbuild/mtest.py", line 1220, in run
    return th.doit()
  File "/usr/lib/python3.8/site-packages/mesonbuild/mtest.py", line 975, in doit
    self.run_tests(tests)
  File "/usr/lib/python3.8/site-packages/mesonbuild/mtest.py", line 1130, in run_tests
    self.drain_futures(futures)
  File "/usr/lib/python3.8/site-packages/mesonbuild/mtest.py", line 1146, in drain_futures
    self.process_test_result(result.result())
  File "/usr/lib/python3.8/concurrent/futures/_base.py", line 432, in result
    return self.__get_result()
  File "/usr/lib/python3.8/concurrent/futures/_base.py", line 388, in __get_result
    raise self._exception
  File "/usr/lib/python3.8/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/usr/lib/python3.8/site-packages/mesonbuild/mtest.py", line 628, in run
    cmd = self._get_cmd()
  File "/usr/lib/python3.8/site-packages/mesonbuild/mtest.py", line 612, in _get_cmd
    elif self.test.cmd_is_built and self.test.needs_exe_wrapper:
AttributeError: 'TestSerialisation' object has no attribute 'cmd_is_built'

To Reproduce

The issue occurred when running the latest version of meson on an already built version of systemd. After removing the build directory I cannot reproduce the issue anymore. Maybe some issue where the new version of meson can't handle serialized data from older versions?

Expected behavior

No crash

system parameters

• Is this a cross build or just a plain native build (for the same computer)?

Not a cross build

• what operating system (e.g. MacOS Catalina, Windows 10, CentOS 8.0, Ubuntu 18.04, etc.)

Python: 3.8.5
Arch Linux

• what meson --version

meson: 0.55.1

• what ninja --version if it's a Ninja build

ninja: 1.10.0

[xclaesse]

Meson uses python's pickle to store data, so a build dir cannot be reused after meson update. That being said, meson usually detect it's a build from an older version and print an error message saying to reconfigure. Looks like "meson test" subcommand is missing that check.