t5520-pull: Add testcases showing spurious conflicts from git pull --rebase

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t5520-pull.sh

@@ -4,6 +4,11 @@ test_description='pulling into void'
 
 . ./test-lib.sh
 
+modify () {
+	sed -e "$1" <"$2" >"$2.x" &&
+	mv "$2.x" "$2"
+}
+
 D=`pwd`
 
 test_expect_success setup '
@@ -160,4 +165,61 @@ test_expect_success 'pull --rebase works on branch yet to be born' '
 	test_cmp expect actual
 '
 
+test_expect_success 'setup for detecting upstreamed changes' '
+	mkdir src &&
+	(cd src &&
+	 git init &&
+	 printf "1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n" > stuff &&
+	 git add stuff &&
+	 git commit -m "Initial revision"
+	) &&
+	git clone src dst &&
+	(cd src &&
+	 modify s/5/43/ stuff &&
+	 git commit -a -m "5->43" &&
+	 modify s/6/42/ stuff &&
+	 git commit -a -m "Make it bigger"
+	) &&
+	(cd dst &&
+	 modify s/5/43/ stuff &&
+	 git commit -a -m "Independent discovery of 5->43"
+	)
+'
+
+test_expect_failure 'git pull --rebase detects upstreamed changes' '
+	(cd dst &&
+	 git pull --rebase &&
+	 test -z "$(git ls-files -u)"
+	)
+'
+
+test_expect_success 'setup for avoiding reapplying old patches' '
+	(cd dst &&
+	 test_might_fail git rebase --abort &&
+	 git reset --hard origin/master
+	) &&
+	git clone --bare src src-replace.git &&
+	rm -rf src &&
+	mv src-replace.git src &&
+	(cd dst &&
+	 modify s/2/22/ stuff &&
+	 git commit -a -m "Change 2" &&
+	 modify s/3/33/ stuff &&
+	 git commit -a -m "Change 3" &&
+	 modify s/4/44/ stuff &&
+	 git commit -a -m "Change 4" &&
+	 git push &&
+
+	 modify s/44/55/ stuff &&
+	 git commit --amend -a -m "Modified Change 4"
+	)
+'
+
+test_expect_failure 'git pull --rebase does not reapply old patches' '
+	(cd dst &&
+	 test_must_fail git pull --rebase &&
+	 test 1 = $(find .git/rebase-apply -name "000*" | wc -l)
+	)
+'
+
 test_done