Do not set None to external_symbolizer_path env variable (#1346). (#1401)
Do not set None to external_symbolizer_path env variable (#1346). (#1401)

* Do not set None to external_symbolizer_path env variable (#1346).

* move _quote_value_if_needed inside the condition

google/clusterfuzz,google/clusterfuzz,google/clusterfuzz,google/clusterfuzz,google/clusterfuzz,google/clusterfuzz,google/clusterfuzz,google/clusterfuzz