Rails4 compatibility of WatcherTest#test_watcher_users

Rails4 has_many returns ActiveRecord::Associations::CollectionProxy not array

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extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012744
Fixed calculation of done_ratio of parent task with child having estimated_time at 0 (#15870).

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extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012745
Adds some test helpers to cleanup tests.

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extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012746
remove redundant empty line from RepositoryMercurialTest

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extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012747