Merge branch 'nd/fetch-pack-shallow-fix' into maint

The recent "short-cut clone connectivity check" topic broke a shallow
repository when a fetch operation tries to auto-follow tags.

* nd/fetch-pack-shallow-fix:
  fetch-pack: do not remove .git/shallow file when --depth is not specified

t/t5500-fetch-pack.sh

@@ -505,4 +505,20 @@ test_expect_success 'test --all, --depth, and explicit tag' '
 	) >out-adt 2>error-adt
 '
 
+test_expect_success 'shallow fetch with tags does not break the repository' '
+	mkdir repo1 &&
+	(
+		cd repo1 &&
+		git init &&
+		test_commit 1 &&
+		test_commit 2 &&
+		test_commit 3 &&
+		mkdir repo2 &&
+		cd repo2 &&
+		git init &&
+		git fetch --depth=2 ../.git master:branch &&
+		git fsck
+	)
+'
+
 test_done