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 blockMasterFromDeletingIndexNFile(String repositoryName) {
        AbstractSnapshotIntegTestCase.<MockRepository>getRepositoryOnMaster(repositoryName).setBlockOnDeleteIndexFile();
    }
    public static void blockMasterFromFinalizingSnapshotOnSnapFile(final String repositoryName) {
        AbstractSnapshotIntegTestCase.<MockRepository>getRepositoryOnMaster(repositoryName).setBlockAndFailOnWriteSnapFiles();
    }
    public static void blockMasterOnAnyDataFile(final String repositoryName) {
        AbstractSnapshotIntegTestCase.<MockRepository>getRepositoryOnMaster(repositoryName).blockOnDataFiles();
    }
    public static void blockMasterOnShardLevelSnapshotFile(final String repositoryName, String indexId) {
        AbstractSnapshotIntegTestCase.<MockRepository>getRepositoryOnMaster(repositoryName).setBlockOnShardLevelSnapFiles(indexId);
    }
    @SuppressWarnings("unchecked")
    public static <T extends Repository> T getRepositoryOnMaster(String repositoryName) {
        return ((T) internalCluster().getCurrentMasterNodeInstance(RepositoriesService.class).repository(repositoryName));
    }
    @SuppressWarnings("unchecked")
    protected static <T extends Repository> T getRepositoryOnNode(String repositoryName, String nodeName) {
        return ((T) internalCluster().getInstance(RepositoriesService.class, nodeName).repository(repositoryName));
    }
    public static String blockNodeWithIndex(final String repositoryName, final String indexName) {
        for (String node : internalCluster().nodesInclude(indexName)) {
            AbstractSnapshotIntegTestCase.<MockRepository>getRepositoryOnNode(repositoryName, node).blockOnDataFiles();
            return node;
        }
        fail("No nodes for the index " + indexName + " found");
        return null;
    }
    public static void blockNodeOnAnyFiles(String repository, String nodeName) {
        AbstractSnapshotIntegTestCase.<MockRepository>getRepositoryOnNode(repository, nodeName).setBlockOnAnyFiles();