lsearch nocase bug or what?

I wanted to use case insensitive list search but I got an error back. Try this proof-of-concept iRule:

when CLIENT_ACCEPTED {
  TCP::collect
}
when CLIENT_DATA {
  set list [split [TCP::payload] foo]
  if { [lsearch -all -nocase $list bar] >= 0 } {
    log local0. "match"
  }
}

What I get back is:

01070151:3: Rule [/Common/TestLsearch] error:

Apart from TCL lsearch specs, this example is even mentioned in Colin's iRules guide Case Insensitive Comparisons

lsearch -all -nocase {a b c a b c} C

I'm running 11.1.0 for reference..

Is this a bug or is there some deeper reason for this?

Jure