Clarification: is the hgmerge program always called?

[Christian Boos]

Hi,

While doing some updates in the Wiki (turning "hg update -m"
into "hg merge"), I was a bit surprised by the explanations
concerning the merge program: it was written that Mercurial
tries to resolve the merge on its own, and only when it fails
to do so, calls an external merge program...
That surprised me as I thought that the hgmerge script (or
the program specified by HGMERGE) was _always_ responsible
for doing the merge.
All the tests I did seems to comfort that idea.

Before modifying the Wiki further, I'd like to have confirmation
on this.

-- Christian