discovery: new devel.discovery.randomize option By default, this is True, but setting it to False is a uniform way to kill all randomness in integration tests such as test-setdiscovery.t By "uniform" we mean that it can be passed to implementations in other languages, for which the monkey-patching of random.sample would be irrelevant. In the above mentioned test file, we use it right away, replacing the adhoc extension that had the same purpose, and to derandomize a case with many round-trips, that we'll need to behave uniformly in the Rust version. Differential Revision: https://phab.mercurial-scm.org/D6427

--- a/mercurial/setdiscovery.py	Tue May 21 17:43:55 2019 +0200
+++ b/mercurial/setdiscovery.py	Tue May 21 17:44:15 2019 +0200
@@ -390,7 +390,9 @@
 
     # full blown discovery
 
-    disco = partialdiscovery(local, ownheads, remote.limitedarguments)
+    randomize = ui.configbool('devel', 'discovery.randomize')
+    disco = partialdiscovery(local, ownheads, remote.limitedarguments,
+                             randomize=randomize)
     # treat remote heads (and maybe own heads) as a first implicit sample
     # response
     disco.addcommons(knownsrvheads)