run: running the same command twice on a callback stage doesn't reproduce

[ghost]

version: 0.35.7+8ef52f

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❯ dvc run -o hello 'echo hello > hello'
Running command:
	echo hello > hello
Saving 'hello' to cache '.dvc/cache'.
Saving information to 'hello.dvc'.

❯ dvc run -o hello 'echo hello > hello'
Stage is cached, skipping.

The second run should have run the command again, as it is a callback stage.