Correct number of `getblockheader` batches following `time` addition, cf #8

bitcoin.py

@@ -29,7 +29,7 @@ def loadHeaders(break_at):
     if not LOAD_FROM_HEADERS_FILE:
         headersNumber = break_at if break_at else int(cli(['getblockcount']))
         headerHashes = pull('getblockhash', list(range(headersNumber)), 2)
-        headers = pull('getblockheader', headerHashes, 3)
+        headers = pull('getblockheader', headerHashes, 4)
     else:
         with open(config.HEADERS_FILE_PATH) as f:
             headers = json.load(f)
@@ -58,4 +58,4 @@ def bits_to_target(bits):
     bitsN = (bits >> 24) & 0xff
     bitsBase = bits & 0xffffff
     target = bitsBase << (8 * (bitsN - 3))
-    return target
\ No newline at end of file
+    return target