Make sure to call ReleaseFileNumberFromPendingOutputs

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/4219

Differential Revision: D9144294

Pulled By: riversand963

fbshipit-source-id: e46b72e5f8a149dc7a0512e38edcd0ddb0150f30

db/db_impl.cc

@@ -2937,6 +2937,8 @@ Status DBImpl::IngestExternalFile(
   }
   dummy_sv_ctx.Clean();
   if (!status.ok()) {
+    InstrumentedMutexLock l(&mutex_);
+    ReleaseFileNumberFromPendingOutputs(pending_output_elem);
     return status;
   }