Merge pull request #2078 from alex/ssh-load-coverage

Improvemed branch coverage for ssh public key loading
diff --git a/src/cryptography/hazmat/backends/openssl/backend.py b/src/cryptography/hazmat/backends/openssl/backend.py
index af66aca..18faecb 100644
--- a/src/cryptography/hazmat/backends/openssl/backend.py
+++ b/src/cryptography/hazmat/backends/openssl/backend.py
@@ -685,8 +685,7 @@
 
     def generate_dsa_parameters(self, key_size):
         if key_size not in (1024, 2048, 3072):
-            raise ValueError(
-                "Key size must be 1024 or 2048 or 3072 bits.")
+            raise ValueError("Key size must be 1024 or 2048 or 3072 bits.")
 
         if (self._lib.OPENSSL_VERSION_NUMBER < 0x1000000f and
                 key_size > 1024):
diff --git a/src/cryptography/hazmat/primitives/serialization.py b/src/cryptography/hazmat/primitives/serialization.py
index 8699fa9..9fbc32b 100644
--- a/src/cryptography/hazmat/primitives/serialization.py
+++ b/src/cryptography/hazmat/primitives/serialization.py
@@ -106,12 +106,11 @@
     if rest:
         raise ValueError('Key body contains extra bytes.')
 
-    if curve_name == b"nistp256":
-        curve = ec.SECP256R1()
-    elif curve_name == b"nistp384":
-        curve = ec.SECP384R1()
-    elif curve_name == b"nistp521":
-        curve = ec.SECP521R1()
+    curve = {
+        b"nistp256": ec.SECP256R1,
+        b"nistp384": ec.SECP384R1,
+        b"nistp521": ec.SECP521R1,
+    }[curve_name]()
 
     if six.indexbytes(data, 0) != 4:
         raise NotImplementedError(