i18n: fix regexp pattern to detect translation for DEPRECATED

Since 44cc9f63a2f1, deprecated commands, options and so on are
detected by "(DEPRECATED)" instead of "DEPRECATED".

Therefore, 'deprecated' checker in i18n/check-translation.py should
check translation, of which msgid contains "(DEPRECATED)" instead of
"DEPRECATED".

At glance, it seems to do so, but it actually doesn't, because Python
regexp treats "()" as grouping of patterns and "(DEPRECATED)" matches
only against "DEPRECATED".

i18n/check-translation.py

@@ -76,7 +76,7 b' def deprecatedsetup(pofile):'
         global deprecatedpe
         deprecatedpe = pes[0]
 
-@fatalchecker('(DEPRECATED)')
+@fatalchecker(r'\(DEPRECATED\)')
 def deprecated(pe):
     """Check for DEPRECATED
     >>> ped = polib.POEntry(
@@ -102,6 +102,10 b' def deprecated(pe):'
     True
     >>> for e in deprecated(pe): print e
     msgstr inconsistently translated (DEPRECATED)
+    >>> pe = polib.POEntry(
+    ...     msgid = 'Something (DEPRECATED, foo bar)',
+    ...     msgstr= 'something (DETACERPED, foo bar)')
+    >>> match(deprecated, pe)
     """
     if not ('(DEPRECATED)' in pe.msgstr or
             (deprecatedpe and deprecatedpe.msgstr and