tests: apply modern idiom for signaling test failure

Simplify the way these tests signal failure by employing the modern
idiom of making the `if` or `case` statement resolve to false when an
error is detected.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t2102-update-index-symlinks.sh

@@ -25,7 +25,7 @@ test_expect_success \
 'the index entry must still be a symbolic link' '
 case "$(git ls-files --stage --cached symlink)" in
 120000" "*symlink) echo pass;;
-*) echo fail; git ls-files --stage --cached symlink; (exit 1);;
+*) echo fail; git ls-files --stage --cached symlink; false;;
 esac'
 
 test_done

t/t3402-rebase-merge.sh

@@ -68,7 +68,7 @@ test_expect_success 'merge and rebase should match' '
 	if test -s difference
 	then
 		cat difference
-		(exit 1)
+		false
 	else
 		echo happy
 	fi
@@ -102,7 +102,7 @@ test_expect_success 'merge and rebase should match' '
 	if test -s difference
 	then
 		cat difference
-		(exit 1)
+		false
 	else
 		echo happy
 	fi
@@ -117,7 +117,7 @@ test_expect_success 'picking rebase' '
 		echo happy
 	else
 		git show-branch
-		(exit 1)
+		false
 	fi &&
 	f=$(git diff-tree --name-only HEAD^ HEAD) &&
 	g=$(git diff-tree --name-only HEAD^^ HEAD^) &&
@@ -127,7 +127,7 @@ test_expect_success 'picking rebase' '
 	*)
 		echo "$f"
 		echo "$g"
-		(exit 1)
+		false
 	esac
 '
 

t/t3700-add.sh

@@ -177,7 +177,7 @@ test_expect_success 'git add --refresh' '
 	git read-tree HEAD &&
 	case "$(git diff-index HEAD -- foo)" in
 	:100644" "*"M	foo") echo pass;;
-	*) echo fail; (exit 1);;
+	*) echo fail; false;;
 	esac &&
 	git add --refresh -- foo &&
 	test -z "$(git diff-index HEAD -- foo)"