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
private final Level level; 
        private final String message;
        public DeprecationWarning(Level level, String message) {
            this.level = level;
            this.message = message;
        }
        @Override
        public int hashCode() {
            return Objects.hash(message);
        }
        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            DeprecationWarning that = (DeprecationWarning) o;
            return Objects.equals(message, that.message);
        }
        @Override
        public String toString() {
            return Strings.format("%s: %s", level.name(), message);
        }
    }
    /**