cros_workon bash completion -- handle flags anywhere.

bash_completion

Index: bash_completion
diff --git a/bash_completion b/bash_completion
index 451cabea66967612c96bddf30531a0811ab99ce2..84214dde34c982dcc3beb94a0972a219c7df7840 100644
--- a/bash_completion
+++ b/bash_completion
@@ -171,9 +171,9 @@ _cros_workon_package_complete() {
 # Complete the cros_workon arguments.
 _cros_workon() {
   COMPREPLY=()
-  _cros_workon_command_complete && return 0
   _flag_complete && return 0
   _complete_board_sysroot_flag && return 0
+  _cros_workon_command_complete && return 0
   _cros_workon_package_complete && return 0
   return 0
 }