Work-around model limitation/bug in PULSE test, bitcask_eqc.erl

In the C65 counterexample below, the {var,2} worker proc tries to
get key #19 and allegedly fails.  The last step of the main proc is
a put loop of keys #1 - #34.  The {var,2} worker is racing with
both the main proc and also with the {var,7} worker that is
doing a fold.  The fold happens first, which freezes the keydir
when the next put happens.  Then the {var,2} worker does its get
and finds (correctly) `not_found` ... but the model is buggy and
can't predict the correct answer.

I'm not good enough at the temporal logic to fix the model
The Correct Way.  So I've patched it up so that any 'bad' thing
detected by the main/1st proc is truly bad.  But if a 'bad' thing
happens in a forked worker, then if we know that there's a fold
happening at the same time, we assume that the model's predicted
answer is bad and thus we *ignore* the 'bad' thing.

    191> C65 = binary_to_term(element(2,file:read_file("zzz.c65@develop@commit=a2d75.bin"))).
    [[{set,{var,2},
           {call,bitcask_eqc,fork,
                 [[{init,{state,undefined,false,false,[]}},
                   {set,{not_var,8},{not_call,bitcask_eqc,bc_open,[false]}}]]}},
      {set,{var,4},
           {call,bitcask_eqc,fork,
                 [[{init,{state,undefined,false,false,[]}},
                   {set,{not_var,2},{not_call,bitcask_eqc,bc_open,[false]}},
                   {set,{not_var,3},
                        {not_call,bitcask_eqc,bc_close,[{not_var,2}]}},
                   {set,{not_var,9},{not_call,bitcask_eqc,bc_open,[false]}},
                   {set,{not_var,10},
                        {not_call,bitcask_eqc,get,[{not_var,9},19]}}]]}},
      {set,{var,6},
           {call,bitcask_eqc,fork,
                 [[{init,{state,undefined,false,false,[]}},
                   {set,{not_var,3},{not_call,bitcask_eqc,bc_open,[false]}}]]}},
      {set,{var,7},
           {call,bitcask_eqc,fork,
                 [[{init,{state,undefined,false,false,[]}},
                   {set,{not_var,5},{not_call,bitcask_eqc,bc_open,[false]}},
                   {set,{not_var,7},
                        {not_call,bitcask_eqc,fold,[{not_var,5}]}}]]}},
      {set,{var,12},
           {call,bitcask_eqc,fork,
                 [[{init,{state,undefined,false,false,[]}},
                   {set,{not_var,3},{not_call,bitcask_eqc,bc_open,[false]}},
                   {set,{not_var,8},
                        {not_call,bitcask_eqc,fold,[{not_var,3}]}}]]}},
      {set,{var,17},{call,bitcask_eqc,bc_open,[true]}},
      {set,{var,28},{call,bitcask_eqc,put,[{var,17},1,<<>>]}},
      {set,{var,29},{call,bitcask_eqc,needs_merge,[{var,17}]}},
      {set,{var,30},{call,bitcask_eqc,fork_merge,[{var,17}]}},
      {set,{var,32},
           {call,bitcask_eqc,puts,[{var,17},{1,34},<<>>]}}],
     {77863,46676,48146},
     [{events,[]}]]