enforce-single-head = yes prevents commit, although there are no multiple heads

[Uwe Brauer]

Hi


I am not sure whether I will be able to produce a script that can
reproduce the error described below because it occurs on a repository 
with some 800 changesets and various branches

When I tried 

[experimental]
enforce-single-head = yes

On a small repository it did what I exspected, namely it prevented me by
using say topics to create multiple heads on a branch.

However when I used this setting on  this huge repository and tried to
commit I obtained 

Waiting for Emacs...
transaction abort!
rollback completed
note: commit message saved in .hg/last-message.txt
abort: 3 heads on "default"
(cbf9827aaa0b, c5126e027526, aa50036267da)

So I deleted the option and commited again, however when running 
hg heads

It returned one head not three 

Can anybody please enlighten me?

Thanks

Uwe Brauer