fix(time,lftest): keep modules importable on Python 3.6 (RHEL 8 / Rocky 8)

time.py guarded the zoneinfo import (stdlib only since 3.9) and falls back to UTC; lftest.py replaced a parenthesized context manager (3.10+ syntax) with an ExitStack. Both modules sit in every plugin's import chain, so the prior code crashed uncompiled plugins on the system Python of RHEL 8 / Rocky 8.

Author: markuslf

CHANGELOG.md

@@ -11,6 +11,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 * db_sqlite.py: cached databases now self-heal after a schema change between releases. A constraint or data error (such as a `NOT NULL` column that a newer or older release no longer writes) deletes and rebuilds the cache on the next run, instead of failing on every run until the stale file is removed by hand.
+* lftest.py: no longer breaks at import with a `SyntaxError` on Python interpreters older than 3.10 (such as the system Python 3.6 on RHEL 8 / Rocky 8, and our supported Python 3.9 floor). A parenthesized context manager was rewritten as nested `with` statements, so every plugin that imports this module stays runnable on those interpreters.
+* time.py: no longer fails to import on Python interpreters older than 3.9 (such as the system Python 3.6 on RHEL 8 / Rocky 8) where the `zoneinfo` module does not exist. Consumers that do not need named time zones keep working and fall back to UTC.
 
 
 ## [v5.0.0] - 2026-06-12

lftest.py

@@ -19,7 +19,7 @@
 from . import base, disk, shell
 
 __author__ = 'Linuxfabrik GmbH, Zurich/Switzerland'
-__version__ = '2026061201'
+__version__ = '2026061901'
 
 
 def run(test_instance, plugin, testcase):
@@ -600,20 +600,24 @@ def run_mysql_compatible_from_containerfile(
     tag = f'lfmp-mysql-{dockerfile_name}'.lower().replace('_', '-')
 
     # No parenthesized context managers: they are Python 3.10+ syntax and break
-    # parsing on RHEL 8's default Python 3.6.
-    with (
-        DockerImage(
-            path=build_dir,
-            dockerfile_path=dockerfile_name,
-            tag=tag,
-            clean_up=False,
-        ) as image,
-        _run_mysql_compatible_resolved(
-            str(image.tag),
-            command,
-            seed,
-        ) as result,
-    ):
+    # parsing on RHEL 8's default Python 3.6. Use an ExitStack so the module
+    # stays importable on the oldest interpreters our plugins run on.
+    with contextlib.ExitStack() as stack:
+        image = stack.enter_context(
+            DockerImage(
+                path=build_dir,
+                dockerfile_path=dockerfile_name,
+                tag=tag,
+                clean_up=False,
+            )
+        )
+        result = stack.enter_context(
+            _run_mysql_compatible_resolved(
+                str(image.tag),
+                command,
+                seed,
+            )
+        )
         yield result
 
 

time.py

@@ -11,12 +11,20 @@
 """Provides datetime functions."""
 
 __author__ = 'Linuxfabrik GmbH, Zurich/Switzerland'
-__version__ = '2026060701'
+__version__ = '2026061901'
 
 import datetime
 import re
 import time
-import zoneinfo
+
+try:
+    import zoneinfo
+except ImportError:
+    # zoneinfo is part of the standard library since Python 3.9. On older
+    # interpreters (such as the system Python 3.6 on RHEL 8 / Rocky 8) it is
+    # missing; degrade to UTC in get_timezone() instead of failing at import,
+    # so consumers that do not need named time zones keep working.
+    zoneinfo = None
 
 
 def epoch2iso(timestamp):
@@ -62,14 +70,16 @@ def get_timezone(tz_name):
     >>> get_timezone('Invalid/Zone').key
     'Etc/UTC'
     """
+    if zoneinfo is None:
+        # Python < 3.9 without the zoneinfo backport
+        return datetime.timezone.utc
     try:
         return zoneinfo.ZoneInfo(tz_name)
     except Exception:
         # Fallback to UTC if the name isn't found
         try:
             return zoneinfo.ZoneInfo('Etc/UTC')
         except Exception:
-            # Python < 3.9
             return datetime.timezone.utc