rust-chg: indent process_message() to prepare mass rewrite to futures-0.3

I'll start upgrading the codebase to modern async/await-based implementation,
which cannot be done incrementally. This is the last non-breaking patch to
prepare for the rewrite.

Differential Revision: https://phab.mercurial-scm.org/D8403

rust/chg/src/runcommand.rs

@@ -140,6 +140,7 where
     C: Connection,
     H: SystemHandler,
 {
+    {
     match msg {
         ChannelMessage::Data(b'r', data) => {
             let code = message::parse_result_code(data)?;
@@ -150,10 +151,9 where
             let msg_loop = MessageLoop::resume(client);
             Ok(AsyncS::PollAgain(CommandState::Running(msg_loop, handler)))
         }
-        ChannelMessage::InputRequest(..) | ChannelMessage::LineRequest(..) => Err(io::Error::new(
-            io::ErrorKind::InvalidData,
-            "unsupported request",
-        )),
+            ChannelMessage::InputRequest(..) | ChannelMessage::LineRequest(..) => Err(
+                io::Error::new(io::ErrorKind::InvalidData, "unsupported request"),
+            ),
         ChannelMessage::SystemRequest(data) => {
             let (cmd_type, cmd_spec) = message::parse_command_spec(data)?;
             match cmd_type {
@@ -169,3 +169,4 where
         }
     }
 }
+}