Make reinitialize_command's return type Generic when "command" argument is a Command #1190

Job	Run time
collateral (diffcov)	45s
test (3.8, ubuntu-latest)	39s
collateral (docs)	28s
ci_setuptools (3.10, ubuntu-latest)	4m 5s
test_cygwin (39, windows-latest)	5m 3s
test (3.8, macos-latest)	53s
test (3.8, windows-latest)	39s
test_msvc_python_mingw	2m 1s
test (3.13, ubuntu-latest)	49s
test_msys2_mingw (mingw64, x86_64, gcc, g++)	1m 38s
test (3.13, macos-latest)	42s
test_msys2_mingw (mingw32, i686, gcc, g++)	1m 51s
test (3.13, windows-latest)	40s
test_msys2_mingw (ucrt64, ucrt-x86_64, gcc, g++)	1m 47s
test (3.9, ubuntu-latest)	41s
test_msys2_mingw (clang64, clang-x86_64, clang, clang++)	1m 44s
test (3.10, ubuntu-latest)	43s
test (3.11, ubuntu-latest)	38s
test (3.12, ubuntu-latest)	45s
test (3.14, ubuntu-latest)	53s
test (pypy3.10, ubuntu-latest)	52s
check	4s
release	0s
	28m 20s

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