odd (lexical?) issue with Rakudo/Parrot

[Chris Fields]

I have submitted a simple 'match' implementation for rakudo (method  
version of m//, RT#56970) and ran into an odd issue.  The current  
version of match which works uses a tail call:

.sub 'match' :method
    .param pmc x
    .return x.ACCEPTS(self)
.end
If I try the following:

.sub 'match' :method
    .param pmc x
    .local pmc match
    match = x.ACCEPTS(self);
    .return (match)
.end

I run into 'Null PMC access in set_pmc_keyed()' with ACCEPTS (below),  
which is failing to get the LexPad:

.sub 'ACCEPTS' :method
    .param pmc topic
    .local pmc match
    match = self(topic)
    $P0 = getinterp
    $P1 = $P0['lexpad';1]
    $P1['$/'] = match
    .return (match)
.end

If I simply change match to mimic ACCEPTS, everything works fine.   
This makes me think something is going on with lexicals, but I'm not  
quite sure.  Am I missing something?

chris