# HG changeset patch
# User Matt Harbison <matt_harbison@yahoo.com>
# Date 1615601957 18000
# Node ID d35063ebd76194ceda2319e2c6a5d7a592f630e3
# Parent  5137896602d92551bc361d1a0a80974dc412be6d
obsutil: maintain a homogenous list when computing successors

In practice, this wasn't a problem because of an internal check for an empty
list, but it avoids the following pytype error:

    File "/mnt/c/Users/Matt/hg/mercurial/obsutil.py", line 823, in successorsandmarkers: No attribute 'markers' on List[nothing] [attribute-error]
      In Union[Any, List[nothing], _succs]

Differential Revision: https://phab.mercurial-scm.org/D10213

diff -r 5137896602d9 -r d35063ebd761 mercurial/obsutil.py
--- a/mercurial/obsutil.py	Fri Mar 12 23:28:56 2021 -0500
+++ b/mercurial/obsutil.py	Fri Mar 12 21:19:17 2021 -0500
@@ -782,7 +782,7 @@
     # closestsuccessors returns an empty list for pruned revisions, remap it
     # into a list containing an empty list for future processing
     if ssets == []:
-        ssets = [[]]
+        ssets = [_succs()]
 
     # Try to recover pruned markers
     succsmap = repo.obsstore.successors