Simplify unit test, so it's not so implementation-specific.

tests/test_resolver.py

@@ -395,17 +395,15 @@ def test_combine_install_requirements_with_paths(from_line, make_package):
         assert str(combined.original_link) == str(fake_package.original_link)
 
 
-def test_combine_install_requirements_for_one_package_with_multiple_extras_reset_prepared(
+def test_combine_install_requirements_for_one_package_with_multiple_extras(
     from_line,
 ):
-    """Regression test for https://github.com/jazzband/pip-tools/pull/1512/files."""
+    """Regression test for https://github.com/jazzband/pip-tools/pull/1512"""
     pkg1 = from_line("ray[default]==1.1.1")
-    pkg1.prepared = True
     pkg2 = from_line("ray[tune]==1.1.1")
     combined = combine_install_requirements([pkg1, pkg2])
 
     assert str(combined) == "ray[default,tune]==1.1.1"
-    assert combined.prepared is False
 
 
 def test_compile_failure_shows_provenance(resolver, from_line):