[meld] filters: Reuse re.compile checking in bytestring regexes

[Kai Willadsen <kaiw src gnome org>]

commit 2a3bb1b5bcc8cc75e16012f6f8e9012ab3921aad
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sun Oct 28 07:10:51 2018 +1000

    filters: Reuse re.compile checking in bytestring regexes

 meld/filters.py | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)
---
diff --git a/meld/filters.py b/meld/filters.py
index 8ec8ec32..c2701511 100644
--- a/meld/filters.py
+++ b/meld/filters.py
@@ -34,7 +34,7 @@ class FilterEntry:
     @classmethod
     def _compile_regex(cls, regex):
         try:
-            compiled = re.compile("(?m)" + regex)
+            compiled = re.compile(regex, re.M)
         except re.error:
             compiled = None
         return compiled
@@ -46,11 +46,7 @@ class FilterEntry:
             # encoding errors with '.'?
             regex = regex.encode('utf8', 'replace')
 
-        try:
-            compiled = re.compile(b"(?m)" + regex)
-        except re.error:
-            compiled = None
-        return compiled
+        return cls._compile_regex(regex)
 
     @classmethod
     def _compile_shell_pattern(cls, pattern):