When enabling the `warn_unused_ignores = True` option of mypy, this
was making the `test_galaxy_packages` tests fail with:
```
mypy .
Traceback (most recent call last):
File "/tmp/gxpkgtestenvu3fgDr/bin/mypy", line 8, in <module>
sys.exit(console_entry())
File "/tmp/gxpkgtestenvu3fgDr/lib/python3.10/site-packages/mypy/__main__.py", line 15, in console_entry
main()
File "mypy/main.py", line 100, in main
File "mypy/main.py", line 182, in run_build
File "mypy/build.py", line 192, in build
File "mypy/build.py", line 266, in _build
File "mypy/build.py", line 2942, in dispatch
File "mypy/build.py", line 3333, in process_graph
File "mypy/build.py", line 3414, in process_fresh_modules
File "mypy/build.py", line 2110, in fix_cross_refs
File "mypy/fixup.py", line 52, in fixup_module
File "mypy/fixup.py", line 127, in visit_symbol_table
File "mypy/lookup.py", line 49, in lookup_fully_qualified
AssertionError: Cannot find component 'util' for 'galaxy.util'
make: *** [Makefile:96: mypy] Error 1
```
Moreover, installing packages in editable mode was hiding some issues
with how files from other packages were accessed.
JUSTIFICATION:
As per @jmchilton:
The package tests should pretend they don't have galaxy_directory()
available because they're meant to be installed into a Python env.
This test is fundamentally not testing anything about the Galaxy data
package - it is testing scripts placed in Galaxy root directory and that
would not be available in an installed Galaxy environment.