CI: Document why we switch from root to nobody

csppfetch/test.py

@@ -1122,6 +1122,11 @@ if __name__ == '__main__':
     #logging.basicConfig(format='%(process)d:%(levelname)s:%(message)s', level=logging.DEBUG)
 
     if os.getuid() == 0:
+        # We cannot run as root as
+        # DownloadFunctionsTests.test_download_already_present_non_writable
+        # needs a file we cannot change the update time on, and we can't stop
+        # root (even with the directory and file non-writable!). So just run
+        # as "nobody", which should work fine
         import pwd
         try:
             pwent = pwd.getpwnam("nobody")