simplemerge: use 3-way markers if mode=='merge3', ignoring number of labels...
simplemerge: use 3-way markers if mode=='merge3', ignoring number of labels
Before this patch, we use a combination of `mode` and `labels` to
decide which marker style to use. That's mostly my own fault because I
was the one who added the `mergediff` as a "mode" instead of adding a
separate argument for marker style. Still, let's make these arguments
more orthogonal by ignoring the number of labels when deciding which
marker style to use.
This refactoring makes it a little clearer in the simplemerge
*extension* that passing more than 2 `--label` arguments changes the
marker style.
Differential Revision:
https://phab.mercurial-scm.org/D11972
