revlog: fix bad indentation (replace tab by space)

mercurial/revlog.py

@@ -1438,7 +1438,7 b' class revlog(object):'
         # We work around this issue by inserting a seek() before writing.
         # Note: This is likely not necessary on Python 3.
         ifh.seek(0, os.SEEK_END)
-	 if dfh:
+        if dfh:
             dfh.seek(0, os.SEEK_END)
 
         curr = len(self) - 1