Prevents clobbering of role_prefix

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extra : source : ce9fc6522408ea7294b548c1c4b1bb44104b4a2e
Changelog entry

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extra : source : faa24f17b2cb6755210338a32bdb0203233859d3
Merge pull request #327 from einhverfr/master

Prevents clobbering of role_prefix