=== modified file 'bzrlib/transport/sftp.py'
--- bzrlib/transport/sftp.py	2016-01-21 17:48:07 +0000
+++ bzrlib/transport/sftp.py	2016-11-27 10:42:09 +0000
@@ -410,8 +410,9 @@
         try:
             path = self._remote_path(relpath)
             f = self._get_sftp().file(path, mode='rb')
+            size = f.stat().st_size
             if self._do_prefetch and (getattr(f, 'prefetch', None) is not None):
-                f.prefetch()
+                f.prefetch(size)
             return f
         except (IOError, paramiko.SSHException), e:
             self._translate_io_exception(e, path, ': error retrieving',

=== modified file 'doc/en/release-notes/bzr-2.7.txt'
--- doc/en/release-notes/bzr-2.7.txt	2016-02-01 18:09:33 +0000
+++ doc/en/release-notes/bzr-2.7.txt	2016-11-27 10:42:09 +0000
@@ -5,6 +5,17 @@
 .. toctree::
    :maxdepth: 1
 
+bzr 2.7.1
+#########
+
+
+Bug Fixes
+*********
+
+* Cope with paramiko making argument to SFTPFile.prefetch() mandatory.
+  (Jelmer Vernooij, #1579093)
+
+
 bzr 2.7.0
 #########