Merge branch '0.10' into 0.11

ChangeLog

@@ -63,6 +63,8 @@ ver. 0.10.5-dev-1 (20??/??/??) - development edition
 -----------
 
 ### Fixes
+* [compatibility] systemd backend: default flags changed to SYSTEM_ONLY(4), fixed in gh-2444 in order to ignore
+  user session files per default, so could prevent "Too many open files" errors on a lot of user sessions (see gh-2392)
 * [grave] fixed parsing of multi-line filters (`maxlines` > 1) together with systemd backend,
   now systemd-filter replaces newlines in message from systemd journal with `\n` (otherwise 
   multi-line parsing may be broken, because removal of matched string from multi-line buffer window

fail2ban/server/filtersystemd.py

@@ -86,10 +86,12 @@ class FilterSystemd(JournalFilter): # pragma: systemd no cover
 				files.extend(glob.glob(p))
 			args['files'] = list(set(files))
 
+		# Default flags is SYSTEM_ONLY(4). This would lead to ignore user session files,
+		# so can prevent "Too many open files" errors on a lot of user sessions (see gh-2392):
 		try:
 			args['flags'] = int(kwargs.pop('journalflags'))
 		except KeyError:
-			pass
+			args['flags'] = 4
 
 		return args