--- a/mercurial/pure/parsers.py	Sat Oct 05 10:29:34 2019 -0400
+++ b/mercurial/pure/parsers.py	Sun Oct 06 09:45:02 2019 -0400
@@ -12,6 +12,7 @@
 
 from ..node import nullid
 from .. import pycompat
+
 stringio = pycompat.bytesio
 
 
@@ -26,17 +27,21 @@
     # x is a tuple
     return x
 
+
 indexformatng = ">Qiiiiii20s12x"
 indexfirst = struct.calcsize('Q')
 sizeint = struct.calcsize('i')
 indexsize = struct.calcsize(indexformatng)
 
+
 def gettype(q):
     return int(q & 0xFFFF)
 
+
 def offset_type(offset, type):
     return int(int(offset) << 16 | type)
 
+
 class BaseIndexObject(object):
     def __len__(self):
         return self._lgt + len(self._extra)
@@ -57,7 +62,7 @@
         if i >= self._lgt:
             return self._extra[i - self._lgt]
         index = self._calculate_index(i)
-        r = struct.unpack(indexformatng, self._data[index:index + indexsize])
+        r = struct.unpack(indexformatng, self._data[index : index + indexsize])
         if i == 0:
             e = list(r)
             type = gettype(e[0])
@@ -65,6 +70,7 @@
             return tuple(e)
         return r
 
+
 class IndexObject(BaseIndexObject):
     def __init__(self, data):
         assert len(data) % indexsize == 0
@@ -81,11 +87,12 @@
         i = i.start
         self._check_index(i)
         if i < self._lgt:
-            self._data = self._data[:i * indexsize]
+            self._data = self._data[: i * indexsize]
             self._lgt = i
             self._extra = []
         else:
-            self._extra = self._extra[:i - self._lgt]
+            self._extra = self._extra[: i - self._lgt]
+
 
 class InlinedIndexObject(BaseIndexObject):
     def __init__(self, data, inline=0):
@@ -100,8 +107,9 @@
             self._offsets = [0] * lgt
         count = 0
         while off <= len(self._data) - indexsize:
-            s, = struct.unpack('>i',
-                self._data[off + indexfirst:off + sizeint + indexfirst])
+            (s,) = struct.unpack(
+                '>i', self._data[off + indexfirst : off + sizeint + indexfirst]
+            )
             if lgt is not None:
                 self._offsets[count] = off
             count += 1
@@ -120,18 +128,20 @@
             self._lgt = i
             self._extra = []
         else:
-            self._extra = self._extra[:i - self._lgt]
+            self._extra = self._extra[: i - self._lgt]
 
     def _calculate_index(self, i):
         return self._offsets[i]
 
+
 def parse_index2(data, inline):
     if not inline:
         return IndexObject(data), None
     return InlinedIndexObject(data, inline), (0, data)
 
+
 def parse_dirstate(dmap, copymap, st):
-    parents = [st[:20], st[20: 40]]
+    parents = [st[:20], st[20:40]]
     # dereference fields so they will be local in loop
     format = ">cllll"
     e_size = struct.calcsize(format)
@@ -141,7 +151,7 @@
     # the inner loop
     while pos1 < l:
         pos2 = pos1 + e_size
-        e = _unpack(">cllll", st[pos1:pos2]) # a literal here is faster
+        e = _unpack(">cllll", st[pos1:pos2])  # a literal here is faster
         pos1 = pos2 + e[4]
         f = st[pos2:pos1]
         if '\0' in f:
@@ -150,6 +160,7 @@
         dmap[f] = e[:4]
     return parents
 
+
 def pack_dirstate(dmap, copymap, pl, now):
     now = int(now)
     cs = stringio()