Fix testr configuration

* Correct passing env vars in testr.conf.
* Use ZUUL_TEST_ROOT correctly when building the tempdir for
  the local git dir for tests.
* Remove some tabs from docs.
* Update test gearman server method override to match current gear.
* Make test_failed_changes more deterministic: this test
  occasionally failed due to races in the test.
* Update the fake logger configuration to match previous usage.

Change-Id: I1850b930e37d9a0fd2e9c8098052cf7df60576af
Reviewed-on: https://review.openstack.org/35404
Reviewed-by: Monty Taylor <mordred@inaugust.com>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins
diff --git a/doc/source/launchers.rst b/doc/source/launchers.rst
index 27c8c01..832321c 100644
--- a/doc/source/launchers.rst
+++ b/doc/source/launchers.rst
@@ -120,8 +120,8 @@
             Refspec: ${ZUUL_REF}
       Branches to build:
         Branch Specifier: ${ZUUL_COMMIT}
-	  Advanced:
-	    Clean after checkout: True
+            Advanced:
+            Clean after checkout: True
 
 That should be sufficient for a job that only builds a single project.
 If you have multiple interrelated projects (i.e., they share a Zuul