Only file unreproducible issue once. (#2536)
Only file unreproducible issue once. (#2536)

If a previous similar unreproducible issue was already filed and closed,
don't file it again to avoid spamming the issue tracker.
google/clusterfuzz,google/clusterfuzz,google/clusterfuzz,google/clusterfuzz,google/clusterfuzz,google/clusterfuzz,google/clusterfuzz,google/clusterfuzz