From @masak

<alksentrs> rakudo​: () .= ()
<p6eval> rakudo f8e959​: ( no output )
<alksentrs> segfaults
* masak checks locally
<masak> alksentrs​: so it does. good catch.
* masak submits rakudobug
<TimToady> () isn't mutable
<TimToady> though it shouldn't dump
<masak> alksentrs++

From @tadzik

On Tue Aug 31 16​:23​:43 2010, masak wrote​:

<alksentrs> rakudo​: () .= ()
<p6eval> rakudo f8e959​: ( no output )
<alksentrs> segfaults
* masak checks locally
<masak> alksentrs​: so it does. good catch.

$ perl6 -e '() .= ()'
Null PMC access in get_string()
  in main program body at line 1

It doesn't segfault now, but is still LTA

The RT System itself - Status changed from 'new' to 'open'

From @moritz

Now dies LTA during compilation​:

===SORRY!===
Method 'isa' not found for invocant of class 'Undef'

From @moritz

rakudo now parses it as ().=''() and dies with

Method '' not found for invocant of class 'Parcel'

which looks good to me.
Closing without tests, because I'm not sure what exactly the desired
behavior is.

@moritz - Status changed from 'open' to 'resolved'