Revert "git-am: add am.threeWay config variable"

This reverts commit d96a275b.

It used to be possible to apply a patch series with "git am mbox"
and then only after seeing a failure, switch to three-way mode via
"git am -3" (no other options or arguments).  The commit being
reverted broke this workflow.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -769,14 +769,6 @@ am.keepcr::
 	by giving '--no-keep-cr' from the command line.
 	See linkgit:git-am[1], linkgit:git-mailsplit[1].
 
-am.threeWay::
-	By default, `git am` will fail if the patch does not apply cleanly. When
-	set to true, this setting tells `git am` to fall back on 3-way merge if
-	the patch records the identity of blobs it is supposed to apply to and
-	we have those blobs available locally (equivalent to giving the `--3way`
-	option from the command line). Defaults to `false`.
-	See linkgit:git-am[1].
-
 apply.ignoreWhitespace::
 	When set to 'change', tells 'git apply' to ignore changes in
 	whitespace, in the same way as the '--ignore-space-change'

Documentation/git-am.txt

@@ -10,7 +10,7 @@ SYNOPSIS
 --------
 [verse]
 'git am' [--signoff] [--keep] [--[no-]keep-cr] [--[no-]utf8]
-	 [--[no-]3way] [--interactive] [--committer-date-is-author-date]
+	 [--3way] [--interactive] [--committer-date-is-author-date]
 	 [--ignore-date] [--ignore-space-change | --ignore-whitespace]
 	 [--whitespace=<option>] [-C<n>] [-p<n>] [--directory=<dir>]
 	 [--exclude=<path>] [--include=<path>] [--reject] [-q | --quiet]
@@ -90,13 +90,10 @@ default.   You can use `--no-utf8` to override this.
 
 -3::
 --3way::
---no-3way::
 	When the patch does not apply cleanly, fall back on
 	3-way merge if the patch records the identity of blobs
 	it is supposed to apply to and we have those blobs
-	available locally. `--no-3way` can be used to override
-	am.threeWay configuration variable. For more information,
-	see am.threeWay in linkgit:git-config[1].
+	available locally.
 
 --ignore-space-change::
 --ignore-whitespace::

git-am.sh

@@ -393,11 +393,6 @@ then
     keepcr=t
 fi
 
-if test "$(git config --bool --get am.threeWay)" = true
-then
-    threeway=t
-fi
-
 while test $# != 0
 do
 	case "$1" in
@@ -409,8 +404,6 @@ it will be removed. Please do not use it anymore."
 		;;
 	-3|--3way)
 		threeway=t ;;
-	--no-3way)
-		threeway=f ;;
 	-s|--signoff)
 		sign=t ;;
 	-u|--utf8)
@@ -680,8 +673,6 @@ fi
 if test "$(cat "$dotest/threeway")" = t
 then
 	threeway=t
-else
-	threeway=f
 fi
 git_apply_opt=$(cat "$dotest/apply-opt")
 if test "$(cat "$dotest/sign")" = t

t/t4150-am.sh

@@ -303,25 +303,6 @@ test_expect_success 'am -3 -p0 can read --no-prefix patch' '
 	git diff --exit-code lorem
 '
 
-test_expect_success 'am with config am.threeWay falls back to 3-way merge' '
-	rm -fr .git/rebase-apply &&
-	git reset --hard &&
-	git checkout -b lorem4 base3way &&
-	test_config am.threeWay 1 &&
-	git am lorem-move.patch &&
-	test_path_is_missing .git/rebase-apply &&
-	git diff --exit-code lorem
-'
-
-test_expect_success 'am with config am.threeWay overridden by --no-3way' '
-	rm -fr .git/rebase-apply &&
-	git reset --hard &&
-	git checkout -b lorem5 base3way &&
-	test_config am.threeWay 1 &&
-	test_must_fail git am --no-3way lorem-move.patch &&
-	test_path_is_dir .git/rebase-apply
-'
-
 test_expect_success 'am can rename a file' '
 	grep "^rename from" rename.patch &&
 	rm -fr .git/rebase-apply &&