Fix a string vs. bytes error under Python 3. Thanks Tim Tisdall for noticing and fixing the problem.

mako/ext/linguaplugin.py

diff --git a/mako/ext/linguaplugin.py b/mako/ext/linguaplugin.py
index 8126df3..aba039c 100644
--- a/mako/ext/linguaplugin.py
+++ b/mako/ext/linguaplugin.py
@@ -26,9 +26,9 @@
     def process_python(self, code, code_lineno, translator_strings):
         source = code.getvalue().strip()
         if source.endswith(compat.b(':')):
-            if source in ('try:', 'else:') or source.startswith('except'):
+            if source in (compat.b('try:'), compat.b('else:')) or source.startswith(compat.b('except')):
                 source = compat.b('') # Ignore try/except and else
-            elif source.startswith('elif'):
+            elif source.startswith(compat.b('elif')):
                 source = source[2:] # Replace "elif" with "if"
             source += compat.b('pass')
             code = io.BytesIO(source)