Make reinitialize_command's return type Generic when "command" argument is a Command #1206

Job	Run time
ci_setuptools (3.10, ubuntu-latest)	4m 26s
collateral (diffcov)	2m 5s
test (3.9, ubuntu-latest)	52s
collateral (docs)	26s
test (3.9, macos-latest)	1m 0s
test (3.9, windows-latest)	46s
test_cygwin (39, windows-latest)	4m 53s
test (3.13, ubuntu-latest)	1m 4s
test_msvc_python_mingw	3m 1s
test (3.13, macos-latest)	53s
test (3.13, windows-latest)	48s
test_msys2_mingw (mingw64, x86_64, gcc, g++)	2m 13s
test (3.10, ubuntu-latest)	46s
test_msys2_mingw (mingw32, i686, gcc, g++)	2m 15s
test (3.11, ubuntu-latest)	56s
test_msys2_mingw (ucrt64, ucrt-x86_64, gcc, g++)	1m 57s
test (3.12, ubuntu-latest)	53s
test_msys2_mingw (clang64, clang-x86_64, clang, clang++)	1m 58s
test (3.14, ubuntu-latest)	1m 1s
test (pypy3.10, ubuntu-latest)	1m 1s
check	2s
release	0s
	33m 16s

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