Fix unisolated git checkout test

This depends on the target dir to exist; `target` does exist unless
a different build dir is used.

src/symbols/git/checkout.rs

@@ -132,7 +132,7 @@ mod test {
       args: RefCell::new(vec![]),
     };
     let checkout: Checkout<DummyCommandRunner, _, _, _, _> =
-      Checkout::new("target", "source", "branch", &c);
+      Checkout::new(".", "source", "branch", &c);
     let start = Instant::now();
     assert!(run(checkout.target_reached()).unwrap());
     let end = Instant::now();
@@ -142,11 +142,11 @@ mod test {
     assert_eq!(
       first_two_args,
       [
-        ["-C", "target", "fetch", "source", "branch"],
-        ["-C", "target", "rev-list", "-1", "HEAD"],
+        ["-C", ".", "fetch", "source", "branch"],
+        ["-C", ".", "rev-list", "-1", "HEAD"],
       ]
     );
-    assert_eq!(args[2], ["-C", "target", "rev-list", "-1", "FETCH_HEAD"]);
+    assert_eq!(args[2], ["-C", ".", "rev-list", "-1", "FETCH_HEAD"]);
 
     assert!((end - start).as_millis() >= 100);
     assert!((end - start).as_millis() < 150);