Fix cluster refresh failed when using pasword file with isCluster mode

[chetratep]

This PR is to fix the bug when using password file with isCluster mode.

This issue #835

[coveralls]

Pull Request Test Coverage Report for Build 210

• 3 of 7 (42.86%) changed or added relevant lines in 1 file are covered.
• 13 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.02%) to 92.009%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
exporter/redis.go	3	7	42.86%
<!--	Total:	3	7	42.86%	-->

Files with Coverage Reduction	New Missed Lines	%
exporter/exporter.go	13	94.36%
<!--	Total:	13		-->

Totals
Change from base Build 196:	0.02%
Covered Lines:	1946
Relevant Lines:	2115

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💛 - Coveralls

[oliver006]

Thanks for the PR, I'll try to review it in the next few days!

[oliver006]

I think this makes sense.

Can you please add a test to confirm the expected behavior is working ?

[chetratep]

Sure, I'll find sometime later to do it.

[oliver006]

Quick bump @chetratep

[oliver006]

Thanks for adding the tests @chetratep !