An incomplete shard snapshot will prevent a shard from moving away from a node (see `SnapshotInProgressAllocationDecider`). That means that when a shard snapshot completes it may become possible to perform some shard movements that previously were not possible, so we should trigger a reroute to start those movements. AFAICT we do not trigger such a reroute today.
test/framework/src/main/java/org/elasticsearch/test/ESTestCase.java
@BeforeClass
    public static void maybeStashClassSecurityManager() {
        if (getTestClass().isAnnotationPresent(WithoutSecurityManager.class)) {
            securityManagerRestorer = BootstrapForTesting.disableTestSecurityManager();
        }
    }
    @AfterClass
    public static void maybeRestoreClassSecurityManager() throws IOException {
        if (securityManagerRestorer != null) {
            securityManagerRestorer.close();
            securityManagerRestorer = null;
        }
    }
    
    
    @BeforeClass
    public static void setFileSystem() throws Exception {
        PathUtilsForTesting.setup();
    }
    @AfterClass
    public static void restoreFileSystem() throws Exception {
        PathUtilsForTesting.teardown();
    }
    
    @BeforeClass
    public static void setContentType() throws Exception {
        Requests.INDEX_CONTENT_TYPE = randomFrom(XContentType.values());
    }
    @AfterClass
    public static void restoreContentType() {