Precommands and builtins

[phy1729]

sudo echo foo should highlight echo as command not builtin; however, this is not true for all precommands (e.g. noglob preserves builtins).

[danielshahaf]

One definite rule is: if the precommand is an external command, the following command words are all external commands (through the end of the simple command, e.g., sudo nice env ls).