revlog: simplify the v0 parser

mercurial/revlog.py

@@ -300,33 +300,16 b' class revlogoldio(object):'
         s = struct.calcsize(indexformatv0)
         index = []
         nodemap =  {nullid: nullrev}
-        n = 0
-        leftover = None
-        while True:
-            if st:
-                data = fp.read(65536)
-            else:
-                # hack for httprangereader, it doesn't do partial reads well
+        n = off = 0
                 data = fp.read()
-            if not data:
-                break
-            if leftover:
-                data = leftover + data
-                leftover = None
-            off = 0
             l = len(data)
-            while off < l:
-                if l - off < s:
-                    leftover = data[off:]
-                    break
+        while off + s <= l:
                 cur = data[off:off + s]
                 off += s
                 e = struct.unpack(indexformatv0, cur)
                 index.append(e)
                 nodemap[e[-1]] = n
                 n += 1
-            if not st:
-                break
 
         return index, nodemap