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.
server/src/main/java/org/elasticsearch/repositories/RepositoriesService.java
try {
            Repository repository = repository(repositoryName);
            assert repository != null; 
            repository.getRepositoryData(listener);
        } catch (Exception e) {
            listener.onFailure(e);
        }
    }
    /**
     * Returns registered repository
     *
     * @param repositoryName repository name
     * @return registered repository
     * @throws RepositoryMissingException if repository with such name isn't registered
     */
    public Repository repository(String repositoryName) {
        Repository repository = repositories.get(repositoryName);
        if (repository != null) {
            return repository;
        }
        repository = internalRepositories.get(repositoryName);
        if (repository != null) {
            return repository;
        }
        throw new RepositoryMissingException(repositoryName);
    }
    /**
     * @return the current collection of registered repositories, keyed by name.
     */
    public Map<String, Repository> getRepositories() {