[PATCH] Don't share a counter when checking for circularity, list_merge().

[Aidan Kehoe]

I beg your pardon, I haven’t yet committed this, despite what the subject to
my last mail said.

 Ar an dara lá déag de mí Deireadh Fómhair, scríobh Aidan Kehoe: 

 > [...]

-- 
“Apart from the nine-banded armadillo, man is the only natural host of
Mycobacterium leprae, although it can be grown in the footpads of mice.”
  -- Kumar & Clark, Clinical Medicine, summarising improbable leprosy research