Fix ImportError reported in issue #24

Author: xolox

requirements.txt

@@ -2,7 +2,7 @@
 
 coloredlogs >= 5.1
 executor >= 21.3
-humanfriendly >= 6.1
+humanfriendly >= 7.1
 naturalsort >= 1.4
 property-manager >= 2.3
 python-dateutil >= 2.2

rotate_backups/cli.py

@@ -1,7 +1,7 @@
 # rotate-backups: Simple command line interface for backup rotation.
 #
 # Author: Peter Odding <peter@peterodding.com>
-# Last Change: February 14, 2020
+# Last Change: February 18, 2020
 # URL: https://github.com/xolox/python-rotate-backups
 
 """
@@ -208,10 +208,10 @@
 
 # External dependencies.
 import coloredlogs
-from coloredlogs import WINDOWS
 from coloredlogs.syslog import enable_system_logging
 from executor import validate_ionice_class
 from humanfriendly import coerce_boolean, parse_path, pluralize
+from humanfriendly.compat import on_windows
 from humanfriendly.terminal import usage
 from verboselogs import VerboseLogger
 
@@ -235,7 +235,7 @@ def main():
     kw = dict(include_list=[], exclude_list=[])
     parallel = False
     use_sudo = False
-    use_syslog = (not WINDOWS)
+    use_syslog = (not on_windows())
     # Internal state.
     selected_locations = []
     # Parse the command line arguments.