BF: fail2ban-regex assertion error caused by miscounted "missed" lines

Caused when removing lines as part of multiline regex, which had been
previously considered missed.

ChangeLog

@@ -20,6 +20,8 @@ ver. 0.9.1 (2014/xx/xx) - better, faster, stronger
    * Handle case when no sqlite library is available for persistent database
    * Only reban once per IP from database on fail2ban restart
    * Nginx filter to support missing server_name. Closes gh-676
+   * fail2ban-regex assertion error caused by miscount missed lines with
+     multiline regex
 
 - New features:
 

bin/fail2ban-regex

@@ -344,6 +344,7 @@ class Fail2banRegex(object):
 					pass
 				else:
 					self._line_stats.matched += 1
+					self._line_stats.missed -= 1
 		return line, ret
 
 	def process(self, test_lines):