Fix custom tracing b58 printing #67

Job	Run time
fmt	7s
build	1m 49s
clippy	1m 35s
tests (mobile-packet-verifier)	1m 24s
tests (file-store)	1m 46s
tests (ingest)	1m 56s
tests (reward-scheduler)	35s
tests (task-manager)	1m 1s
tests-postgres (boost-manager)	2m 10s
tests-postgres (iot-config)	2m 17s
tests-postgres (iot-packet-verifier)	3m 24s
tests-postgres (iot-verifier)	2m 26s
tests-postgres (mobile-config)	2m 3s
tests-postgres (mobile-verifier)	2m 25s
build-release	0s
	24m 58s

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