# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@octobus.net>
# Date 1669646931 -3600
# Node ID fa955e3f6aee4369f41557b3d2e123709c02ea0c
# Parent  e45590649888314807541e7eb4d4b7521558192f
emitrevision: add a small closure to check if a base is usable

We will make more use of this and make it more complex too.

diff -r e45590649888 -r fa955e3f6aee mercurial/utils/storageutil.py
--- a/mercurial/utils/storageutil.py	Thu Dec 08 15:13:17 2022 +0100
+++ b/mercurial/utils/storageutil.py	Mon Nov 28 15:48:51 2022 +0100
@@ -391,6 +391,9 @@
     # Set of revs available to delta against.
     available = set()
 
+    def is_usable_base(rev):
+        return rev != nullrev and rev in available
+
     for rev in revs:
         if rev == nullrev:
             continue
@@ -420,7 +423,7 @@
         elif deltaparentrev != nullrev:
             # Base revision was already emitted in this group. We can
             # always safely use the delta.
-            if deltaparentrev in available:
+            if is_usable_base(deltaparentrev):
                 baserev = deltaparentrev
 
             # Base revision is a parent that hasn't been emitted already.