skip "do not retry when permissions denied" test if running as root

we can not take away read permissions for root,
so the test would fail.

src/borg/testsuite/__init__.py

@@ -18,6 +18,7 @@
 
 from ..xattr import get_all
 from ..platform import get_flags
+from ..platformflags import is_win32
 from ..helpers import umount
 from ..helpers import EXIT_SUCCESS, EXIT_WARNING, EXIT_ERROR
 from .. import platform
@@ -66,6 +67,14 @@ def unopened_tempfile():
         yield os.path.join(tempdir, "file")
 
 
+def is_root():
+    """return True if running with high privileges, like as root"""
+    if is_win32:
+        return False  # TODO
+    else:
+        return os.getuid() == 0
+
+
 @functools.lru_cache
 def are_symlinks_supported():
     with unopened_tempfile() as filepath:

src/borg/testsuite/archiver/create_cmd.py

@@ -25,6 +25,7 @@
     is_utime_fully_supported,
     is_birthtime_fully_supported,
     same_ts_ns,
+    is_root,
 )
 from . import (
     ArchiverTestCaseBase,
@@ -219,6 +220,7 @@ def test_create_erroneous_file(self):
         assert "input/file2" in out
         assert "input/file3" in out
 
+    @pytest.mark.skipif(is_root(), reason="test must not be run as (fake)root")
     def test_create_no_permission_file(self):
         file_path = os.path.join(self.input_path, "file")
         self.create_regular_file(file_path + "1", size=1000)
@@ -228,6 +230,7 @@ def test_create_no_permission_file(self):
         if is_win32:
             subprocess.run(["icacls.exe", file_path + "2", "/deny", "everyone:(R)"])
         else:
+            # note: this will NOT take away read permissions for root
             os.chmod(file_path + "2", 0o000)
         self.cmd(f"--repo={self.repository_location}", "rcreate", RK_ENCRYPTION)
         flist = "".join(f"input/file{n}\n" for n in range(1, 4))