piem-am: Call git-am with --3way

I think I left this out initially with the idea that the user can (and
should) set am.threeWay to true.  But I can't come up with a reason
why a caller wouldn't want to fall back to a 3-way merge [*], so pass
--3way as an explicit argument to benefit users that haven't
configured am.threeWay.  Now that piem-am-args exists, a user can
always remove it if desired.

[*] And magit-am has had --3way on by default for a long time; I don't
    recall any complaints.

1 files changed, 1 insertions, 1 deletions

diff --git a/piem.el b/piem.el
index 6551c82..49c074d 100644
--- a/piem.el
+++ b/piem.el
@@ -521,7 +521,7 @@ in `piem-default-branch-function'."
               (piem--shorten-subject subject)
               (and version (concat "__" version))))))
 
-(defvar piem-am-args (list "--scissors"))
+(defvar piem-am-args (list "--scissors" "--3way"))
 
 ;;;###autoload
 (defun piem-am (mbox &optional info coderepo)