use environment variable for extacting SCM repositories in ci.rake

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extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012426
make IssuesHelperTest passes when config.threadsafe! is enabled (#12097)

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extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012427
make WatchersHelperTest passes when config.threadsafe! is enabled (#12097)

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extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012428
Fixed multiple scrollbars in project tree (#15741).

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extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012435
use environment variable for running independent tests (units etc.) in ci.rake

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extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012437
Fixed that OpenID authentication fails with 422 error due to token verification (#15735).

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extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012438