jenkins-build: make pylint handle the hashlib hash classes properly

hashlib uses some magic to load whatever is built into the local openssl.
pylint gets confused by this, so we need a pylint plugin to trick pylint
into thinking everything is good.

.pylint-plugins/astng_hashlib.py

@@ -0,0 +1,39 @@
+#
+# started from http://www.logilab.org/blogentry/78354
+#
+
+from logilab.astng import MANAGER
+from logilab.astng.builder import ASTNGBuilder
+
+def hashlib_transform(module):
+    if module.name == 'hashlib':
+        fake = ASTNGBuilder(MANAGER).string_build('''
+
+class fakehash(object):
+  digest_size = -1
+  def __init__(self, value): pass
+  def digest(self):
+    return u''
+  def hexdigest(self):
+    return u''
+  def update(self, value): pass
+
+class md5(fakehash):
+  pass
+
+class sha1(fakehash):
+  pass
+
+class sha256(fakehash):
+  pass
+
+''')
+        for hashfunc in ('sha256', 'sha1', 'md5'):
+            module.locals[hashfunc] = fake.locals[hashfunc]
+
+def register(linter):
+    """called when loaded by pylint --load-plugins, register our tranformation
+    function here
+    """
+    MANAGER.register_transformer(hashlib_transform)
+