FIX #606, correct URL for categories if Blog is on /home #632

Job	Run time
CI / Generate matrix	12s
CI / Context	1s
CI / Check governance	0s
CI / 8.1 prf-low mysql57 phpunit blog	2m 37s
CI / 8.2 mariadb phpunit blog	2m 4s
CI / 8.3 mysql80 phpunit blog	2m 10s
CI / 8.3 mysql84 phpunit blog	2m 6s
CI / 8.1 mysql57 phplinting	2m 9s
CI / 8.1 mysql57 endtoend root	4m 9s
CI / 8.3 mysql80 endtoend root	4m 15s
CI / 8.1 mysql57 js	4m 6s
CI / Dispatch tag patch release	0s
	23m 49s

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