Today if we detect concurrent modification of a snapshot repository then we mark it with `CORRUPTED_REPO_GEN` which blocks further writes to try and prevent additional damage to its contents. You can remove the marker by calling the register-repository API again, but this API will discard no-op re-registrations without taking any action. You can work around this by unregistering the repository first (which may be impossible if it's still in use for searchable snapshots) or by re-registering it with some trivial setting change (which seems hacky).

We should not consider it a no-op re-registration if the repository is currently marked with `CORRUPTED_REPO_GEN`, because doing this re-registration will re-read the repo contents and clear the corruption marker and therefore is not a no-op.
test/framework/src/main/java/org/elasticsearch/snapshots/AbstractSnapshotIntegTestCase.java
}
    public static void blockDataNode(String repository, String nodeName) {
        AbstractSnapshotIntegTestCase.<MockRepository>getRepositoryOnNode(repository, nodeName).blockOnDataFiles();
    }
    public static void blockAndFailDataNode(String repository, String nodeName) {
        AbstractSnapshotIntegTestCase.<MockRepository>getRepositoryOnNode(repository, nodeName).blockAndFailOnDataFiles();
    }
    public static void blockAllDataNodes(String repository) {
        for (RepositoriesService repositoriesService : internalCluster().getDataNodeInstances(RepositoriesService.class)) {
            ((MockRepository) repositoriesService.repository(repository)).blockOnDataFiles();
        }
    }
    public static void unblockAllDataNodes(String repository) {
        for (RepositoriesService repositoriesService : internalCluster().getDataNodeInstances(RepositoriesService.class)) {
            ((MockRepository) repositoriesService.repository(repository)).unblock();
        }
    }
    public static void failReadsAllDataNodes(String repository) {
        for (RepositoriesService repositoriesService : internalCluster().getDataNodeInstances(RepositoriesService.class)) {
            MockRepository mockRepository = (MockRepository) repositoriesService.repository(repository);
            mockRepository.setFailReadsAfterUnblock(true);
        }
    }
    public static void waitForBlockOnAnyDataNode(String repository) throws InterruptedException {
        final boolean blocked = waitUntil(() -> {
            for (RepositoriesService repositoriesService : internalCluster().getDataNodeInstances(RepositoriesService.class)) {
                MockRepository mockRepository = (MockRepository) repositoriesService.repository(repository);
                if (mockRepository.blocked()) {
                    return true;
                }