Snakemake version
9.1.1

Describe the bug
To my surprise, changes to shell directive content don't seem to trigger reruns anymore.

Minimal example

1. Set up Snakefile like this:

rule a:
    output:
        "a.txt",
    shell:
        "echo a > {output}"

2. Run snakemake
3. Edit the content of shell directive to echo b > {output}
4. Run snakemake again

Expected result: Rule reruns
Actual result: Nothing to be done

I installed snakemake v8.30.0 and that one shows expected behavior. So it seems to be a regression in v9 (or if it's intended behavior then it's a breaking change of v9 that isn't documented as far as I can tell)