Eliminate hashlib requirement

If the hashlib module does not exist, use sha and md5 modules instead
to support Python 2.4.  The hashlib module was added to Python 2.5.
Signed-off-by: Nate Case <ncase@xes-inc.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

apps/patchwork/models.py

@@ -28,7 +28,6 @@ import re
 import datetime, time
 import string
 import random
-import hashlib
 from email.mime.text import MIMEText
 import email.utils
 
@@ -167,10 +166,27 @@ class HashField(models.Field):
 
     def __init__(self, algorithm = 'sha1', *args, **kwargs):
         self.algorithm = algorithm
+        try:
+            import hashlib
+            self.hashlib = True
+        except ImportError:
+            self.hashlib = False
+            if algorithm == 'sha1':
+                import sha
+                self.hash_constructor = sha.new
+            elif algorithm == 'md5':
+                import md5
+                self.hash_constructor = md5.new
+            else:
+                raise NameError("Unknown algorithm '%s'" % algorithm)
+            
         super(HashField, self).__init__(*args, **kwargs)
 
     def db_type(self):
-        n_bytes = len(hashlib.new(self.algorithm).digest())
+        if self.hashlib:
+            n_bytes = len(hashlib.new(self.algorithm).digest())
+        else:
+            n_bytes = len(self.hash_constructor().digest())
 	if settings.DATABASE_ENGINE == 'postgresql':
 	    return 'bytea'
 	elif settings.DATABASE_ENGINE == 'mysql':

apps/patchwork/parser.py

@@ -21,7 +21,12 @@
 
 
 import re
-import hashlib
+try:
+    import hashlib
+    sha1_hash = hashlib.sha1
+except ImportError:
+    import sha
+    sha1_hash = sha.sha
 
 _hunk_re = re.compile('^\@\@ -\d+(?:,(\d+))? \+\d+(?:,(\d+))? \@\@')
 _filename_re = re.compile('^(---|\+\+\+) (\S+)')
@@ -158,7 +163,7 @@ def patch_hash(str):
     lines = str.split('\n')
 
     prefixes = ['-', '+', ' ']
-    hash = hashlib.sha1()
+    hash = sha1_hash()
 
     for line in str.split('\n'):