Move SFTPClient.get() termination condition to loop end.

Ensures callback always executes even for zero-len files.

Fixes #90

NEWS

@@ -15,6 +15,10 @@ Releases
 v1.8.1 (DD MM YYYY)
 -------------------
 
+* #90: Ensure that callbacks handed to `SFTPClient.get()` always fire at least
+  once, even for zero-length files downloaded. Thanks to Github user `@enB` for
+  the catch.
+
 
 v1.8.0 (3rd Oct 2012)
 ---------------------

paramiko/sftp_client.py

@@ -612,12 +612,12 @@ class SFTPClient (BaseSFTP):
                 size = 0
                 while True:
                     data = fr.read(32768)
-                    if len(data) == 0:
-                        break
                     fl.write(data)
                     size += len(data)
                     if callback is not None:
                         callback(size, file_size)
+                    if len(data) == 0:
+                        break
             finally:
                 fl.close()
         finally: