Merge branch 'rl/am-3way-config'

"git am" learned am.threeWay configuration variable.

* rl/am-3way-config:
  git-am: add am.threeWay config variable
  t4150-am: refactor am -3 tests
  git-am.sh: fix initialization of the threeway variable

git-am.sh

@@ -378,6 +378,7 @@ committer_date_is_author_date=
 ignore_date=
 allow_rerere_autoupdate=
 gpg_sign_opt=
+threeway=
 
 if test "$(git config --bool --get am.messageid)" = true
 then
@@ -389,6 +390,11 @@ then
     keepcr=t
 fi
 
+if test "$(git config --bool --get am.threeWay)" = true
+then
+    threeway=t
+fi
+
 while test $# != 0
 do
 	case "$1" in
@@ -400,6 +406,8 @@ it will be removed. Please do not use it anymore."
 		;;
 	-3|--3way)
 		threeway=t ;;
+	--no-3way)
+		threeway=f ;;
 	-s|--signoff)
 		sign=t ;;
 	-u|--utf8)
@@ -657,6 +665,8 @@ fi
 if test "$(cat "$dotest/threeway")" = t
 then
 	threeway=t
+else
+	threeway=f
 fi
 git_apply_opt=$(cat "$dotest/apply-opt")
 if test "$(cat "$dotest/sign")" = t