obscache: use 'nullid' as the hash of an empty obsstore
This align this result with what we use for 'emptykey'
--- a/hgext3rd/evolve/obscache.py Fri May 12 18:56:56 2017 +0200
+++ b/hgext3rd/evolve/obscache.py Fri May 12 19:04:13 2017 +0200
@@ -79,7 +79,12 @@
except (OSError, IOError) as e:
if e.errno != errno.ENOENT:
raise
- key = hashlib.sha1(keydata).digest()
+ if keydata:
+ key = hashlib.sha1(keydata).digest()
+ else:
+ # reusing an existing "empty" value make it easier to define a
+ # default cachekey for 'no data'.
+ key = node.nullid
return obsstoresize, key
obsstore.__class__ = cachekeyobsstore