[xml] Restore protocol compatibility with 8.6.

By default, we serialize messages to the "rich printing
representation" as it was done in 8.6, this ways clients don't have to
adapt unless they specifically request the new format using option
`--xml_format=Ppcmds`

1 files changed, 5 insertions, 1 deletions

diff --git a/stm/workerLoop.ml b/stm/workerLoop.ml
index 56fcf8537f..50b42512cb 100644
--- a/stm/workerLoop.ml
+++ b/stm/workerLoop.ml
@@ -6,9 +6,13 @@
 (*         *       GNU Lesser General Public License Version 2.1        *)
 (************************************************************************)
 
-let rec parse args = args
+let rec parse = function
+  | "--xml_format=Ppcmds" :: rest -> parse rest
+  | x :: rest -> x :: parse rest
+  | [] -> []
 
 let loop init args =
+  let args = parse args in
   Flags.make_silent true;
   init ();
   CoqworkmgrApi.init !Flags.async_proofs_worker_priority;