metrics: Use vpython3 instead of sys.executable

Apparently, uploading metrics might happen after sys.executable
has been deleted.

Bug: 1068263
Change-Id: Id4ab465bb97d146b688f42fb2002e29372e65555
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2148879
Commit-Queue: Anthony Polito <apolito@google.com>
Reviewed-by: Anthony Polito <apolito@google.com>
diff --git a/metrics.py b/metrics.py
index 7b8d04a..4df1a8e 100644
--- a/metrics.py
+++ b/metrics.py
@@ -184,7 +184,7 @@
     # We invoke a subprocess, and use stdin.write instead of communicate(),
     # so that we are able to return immediately, leaving the upload running in
     # the background.
-    p = subprocess.Popen([sys.executable, UPLOAD_SCRIPT], stdin=subprocess.PIPE)
+    p = subprocess.Popen(['vpython3', UPLOAD_SCRIPT], stdin=subprocess.PIPE)
     p.stdin.write(json.dumps(self._reported_metrics).encode('utf-8'))
 
   def _collect_metrics(self, func, command_name, *args, **kwargs):