diff --git a/src/allmydata/scripts/tahoe_backup.py b/src/allmydata/scripts/tahoe_backup.py
index 02044ede4..e796061e5 100644
--- a/src/allmydata/scripts/tahoe_backup.py
+++ b/src/allmydata/scripts/tahoe_backup.py
@@ -269,6 +269,7 @@ class BackerUpper(object):
             self.verboseprint("skipping %s.." % quote_local_unicode_path(childpath))
             return False, bdb_results.was_uploaded(), metadata
 
+
 def backup(options):
     bu = BackerUpper(options)
     return bu.run()
@@ -306,7 +307,6 @@ def collect_backup_targets(root, listdir, filter_children):
         yield DirectoryTarget(root)
 
 
-
 def run_backup(
         warn,
         upload_file,
@@ -327,12 +327,10 @@ def run_backup(
     return progress.backup_finished()
 
 
-
 class FileTarget(object):
     def __init__(self, path):
         self._path = path
 
-
     def __repr__(self):
         return "<File {}>".format(self._path)
 
@@ -349,16 +347,13 @@ class FileTarget(object):
             return progress.reused_file(self._path, childcap, metadata)
 
 
-
 class DirectoryTarget(object):
     def __init__(self, path):
         self._path = path
 
-
     def __repr__(self):
         return "<Directory {}>".format(self._path)
 
-
     def backup(self, progress, upload_file, upload_directory):
         metadata = get_local_metadata(self._path)
         progress, create, compare = progress.consume_directory(self._path)
@@ -368,7 +363,6 @@ class DirectoryTarget(object):
         return progress.reused_directory(self._path, dircap, metadata)
 
 
-
 class _ErrorTarget(object):
     def __init__(self, path, isdir):
         self._path = path
@@ -376,19 +370,16 @@ class _ErrorTarget(object):
         self._isdir = isdir
 
 
-
 class PermissionDeniedTarget(_ErrorTarget):
     def backup(self, progress, upload_file, upload_directory):
         return progress.permission_denied(self._isdir, self._quoted_path)
 
 
-
 class FilenameUndecodableTarget(_ErrorTarget):
     def backup(self, progress, upload_file, upload_directory):
         return progress.decoding_failed(self._isdir, self._quoted_path)
 
 
-
 class LinkTarget(_ErrorTarget):
     def backup(self, progress, upload_file, upload_directory):
         return progress.unsupported_filetype(
@@ -398,7 +389,6 @@ class LinkTarget(_ErrorTarget):
         )
 
 
-
 class SpecialTarget(_ErrorTarget):
     def backup(self, progress, upload_file, upload_directory):
         return progress.unsupported_filetype(
@@ -408,7 +398,6 @@ class SpecialTarget(_ErrorTarget):
         )
 
 
-
 class BackupComplete(object):
     def __init__(self,
                  start_timestamp,
@@ -431,11 +420,9 @@ class BackupComplete(object):
         self._directories_skipped = directories_skipped
         self.dircap = dircap
 
-
     def any_skips(self):
         return self._files_skipped or self._directories_skipped
 
-
     def report(self, verbosity, files_checked, directories_checked):
         result = []
 
@@ -470,7 +457,6 @@ class BackupComplete(object):
         return "\n".join(result)
 
 
-
 class BackupProgress(object):
     # Would be nice if this data structure were immutable and its methods were
     # transformations that created a new slightly different object.  Not there
@@ -489,7 +475,6 @@ class BackupProgress(object):
         self._create_contents = {}
         self._compare_contents = {}
 
-
     def report(self, now):
         report_format = (
             "Backing up {target_progress}/{target_total}... {elapsed} elapsed..."
@@ -507,7 +492,6 @@ class BackupProgress(object):
             elapsed=self._format_elapsed(now - self._start_timestamp),
         )
 
-
     def _format_elapsed(self, elapsed):
         seconds = elapsed.total_seconds()
         hours = int(seconds / 3600)
@@ -533,7 +517,6 @@ class BackupProgress(object):
             self.last_dircap,
         )
 
-
     def consume_directory(self, dirpath):
         return self, {
             os.path.basename(create_path): create_value
@@ -547,7 +530,6 @@ class BackupProgress(object):
             if os.path.dirname(compare_path) == dirpath
         }
 
-
     def created_directory(self, path, dircap, metadata):
         self._create_contents[path] = ("dirnode", dircap, metadata)
         self._compare_contents[path] = dircap
@@ -555,7 +537,6 @@ class BackupProgress(object):
         self.last_dircap = dircap
         return self
 
-
     def reused_directory(self, path, dircap, metadata):
         self._create_contents[path] = ("dirnode", dircap, metadata)
         self._compare_contents[path] = dircap
@@ -563,21 +544,18 @@ class BackupProgress(object):
         self.last_dircap = dircap
         return self
 
-
     def created_file(self, path, cap, metadata):
         self._create_contents[path] = ("filenode", cap, metadata)
         self._compare_contents[path] = cap
         self._files_created += 1
         return self
 
-
     def reused_file(self, path, cap, metadata):
         self._create_contents[path] = ("filenode", cap, metadata)
         self._compare_contents[path] = cap
         self._files_reused += 1
         return self
 
-
     def permission_denied(self, isdir, quoted_path):
         return self._skip(
             "WARNING: permission denied on {kind} {path}",
@@ -585,7 +563,6 @@ class BackupProgress(object):
             path=quoted_path,
         )
 
-
     def decoding_failed(self, isdir, quoted_path):
         return self._skip(
             "WARNING: could not list {kind} {path} due to a filename encoding error",
@@ -593,7 +570,6 @@ class BackupProgress(object):
             path=quoted_path,
         )
 
-
     def unsupported_filetype(self, isdir, quoted_path, filetype):
         return self._skip(
             "WARNING: cannot backup {filetype} {path}",
@@ -602,7 +578,6 @@ class BackupProgress(object):
             filetype=filetype,
         )
 
-
     def _skip(self, message, isdir, **kw):
         if isdir:
             self._directories_skipped += 1