fix: fix falsely triggered reruns if input files are obtained via wor…

…kflow.source_path() (#1862)

### Description

<!--Add a description of your PR here-->

### QC
<!-- Make sure that you can tick the boxes below. -->

* [x] The PR contains a test case for the changes or the changes are
already covered by an existing test case.
* [x] The documentation (`docs/`) is updated to reflect the changes or
this is not necessary (e.g. if the change does neither modify the
language nor the behavior or functionalities of Snakemake).

snakemake/persistence.py

@@ -20,6 +20,7 @@
 from snakemake.logging import logger
 from snakemake.jobs import jobfiles
 from snakemake.utils import listfiles
+from snakemake.io import is_flagged, get_flag_value
 
 
 class Persistence:
@@ -419,7 +420,12 @@ def _conda_env(self, job):
 
     @lru_cache()
     def _input(self, job):
-        return sorted(job.input)
+        get_path = (
+            lambda f: get_flag_value(f, "sourcecache_entry").get_path_or_uri()
+            if is_flagged(f, "sourcecache_entry")
+            else f
+        )
+        return sorted(get_path(f) for f in job.input)
 
     @lru_cache()
     def _log(self, job):