wireproto: crude support for version 2 HTTP peer As part of implementing the server-side bits of the wire protocol command handlers for version 2, we want a way to easily test those commands. Currently, we use the "httprequest" action of `hg debugwireproto`. But this requires explicitly specifying the HTTP request headers, low-level frame details, and the data structure to encode with CBOR. That's a lot of boilerplate and a lot of it can change as the wire protocol evolves. `hg debugwireproto` has a mechanism to issue commands via the peer interface. That is *much* easier to use and we prefer to test with that going forward. This commit implements enough parts of the peer API to send basic requests via the HTTP version 2 transport. The peer code is super hacky. Again, the goal is to facilitate server testing, not robustly implement a client. The client code will receive love at a later time. Differential Revision: https://phab.mercurial-scm.org/D3177

--- a/tests/wireprotohelpers.sh	Mon Mar 26 15:34:52 2018 -0700
+++ b/tests/wireprotohelpers.sh	Wed Mar 28 15:09:34 2018 -0700
@@ -5,6 +5,10 @@
   hg --verbose debugwireproto --peer raw http://$LOCALIP:$HGPORT/
 }
 
+sendhttpv2peer() {
+  hg --verbose debugwireproto --peer http2 http://$LOCALIP:$HGPORT/
+}
+
 cat > dummycommands.py << EOF
 from mercurial import (
     wireprototypes,