hgcommands: show milliseconds on RUST_LOG output

Summary: This makes it a bit easier to track down perf issues printed by RUST_LOGs.

Reviewed By: sfilipco

Differential Revision: D23095463

fbshipit-source-id: 78221a1992389f512fac6e6e633be6d19123e04a

eden/scm/lib/hgcommands/src/run.rs

@@ -73,7 +73,7 @@ pub fn run_command(args: Vec<String>, io: &mut clidispatch::io::IO) -> i32 {
 
     // env_logger cannot be inited twice. So this will fail (as expected)
     // if hgcommands is nested (ex. for "hg continue").
-    let _ = env_logger::try_init();
+    let _ = env_logger::builder().format_timestamp_millis().try_init();
 
     let exit_code = {
         let _guard = span.enter();