FileStampDataCacher looks for pages in an incorrect location

[GiovanH]

Pelican version: 4.9.1 (git)
Python version: 3.11.5

Caching settings:

CACHE_CONTENT = True
CHECK_MODIFIED_METHOD = 'mtime'
LOAD_CONTENT_CACHE = True
CONTENT_CACHING_LAYER = 'reader'  # reader or generator

After manually setting the slugs of some pages, I'm seeing errors in the form of

           WARNING  Cannot get modification stamp for                                                             cache.py:125
                    [...]pelican-blog\content\pages\recommendations\unsorted
                            [WinError 2] The system cannot find the file specified:
                    '[...]pelican-blog\\content\\pages\\recommendations\\unsorted'

The page header is in the form of

---
Title: Recommendations: Unsorted
slug: recommendations/unsorted
date: 1970-01-01
Status: hidden
---

What stands out to me is that the source file is not content\pages\recommendations\unsorted. In my case, I've changed it to content\pages\recommendations\unsorted test.md.

Is the cacher (

pelican/pelican/cache.py

Line 4 in 4ca1454

import pickle

) incorrectly basing the source file logic on the expected slug, instead of the source file?