Snakemake version
tested with :
8.10.8
7.32.3

Describe the bug
I have a snakefile using the Rule object to reference outputs from previous rules.
I have a second snakefile in which I want to import some of the rules from first snakefile.
Doing so, Snakemake raises a WorkflowError, that is not raised if I use strings for inputs/outputs instead of using input: rules.somerule.output

Logs

WorkflowError in file imported.smk, line 8:
Rule a is not defined in this workflow. Available rules: 

Minimal example
You can create the 2 following files to recreate the bug :

# main.smk

module imported:
    snakefile: "imported.smk"

rule a:
    output: "a.from_main.txt"
    shell: "touch {output}"

use rule b from imported as b with:
    input: rules.a.output

rule target:
    input: 
        rules.b.output

# imported.smk

rule a:
    output: "a.from_imported.txt"
    shell: "touch {output}"

rule b:
    input: rules.a.output
    output: "b.txt"
    shell: "touch {output}"

rule target:
    input: 
        "b.txt",

And run :

snakemake -s main.smk target -n

doing the following change to imported.smk fixes the error

rule b:
    # input: rules.a.output
    input: "a.from_imported.txt"
    output: "b.txt"
    shell: "touch {output}"