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/internalClusterTest/java/org/elasticsearch/snapshots/ConcurrentSnapshotsIT.java
);
        assertThat(
            cse.getMessage(),
            containsString(
                "Cannot start another operation, already running ["
                    + limitToTest
                    + "] operations and the current limit for concurrent snapshot operations is set to ["
                    + limitToTest
                    + "]"
            )
        );
        boolean deleteAndAbortAll = false;
        if (deleteFuture == null && randomBoolean()) {
            deleteFuture = client().admin().cluster().prepareDeleteSnapshot(repoName, "*").execute();
            deleteAndAbortAll = true;
            if (randomBoolean()) {
                awaitNDeletionsInProgress(1);
            }
        }
        unblockNode(repoName, masterName);
        if (deleteFuture != null) {
            assertAcked(deleteFuture.get());
        }
        if (deleteAndAbortAll) {
            awaitNumberOfSnapshotsInProgress(0);
            for (ActionFuture<CreateSnapshotResponse> snapshotFuture : snapshotFutures) {
                
                
                assertBusy(() -> assertTrue(snapshotFuture.isDone()));
            }