why does integration:test also execute unit tests? (line 18-22 and 24)

gistfile1.sh

> test:test
unit: should include file:/Users/patric/Dropbox/tmp/sbt/src/test/scala/com/springer/core/functional/foo/FunctionalTest.scala => false
unit: should include file:/Users/patric/Dropbox/tmp/sbt/src/test/scala/com/springer/core/integration/foo/IntegrationTest.scala => false
unit: should include file:/Users/patric/Dropbox/tmp/sbt/src/test/scala/com/springer/core/shared/utils/Clock.scala => true
unit: should include file:/Users/patric/Dropbox/tmp/sbt/src/test/scala/com/springer/core/system/foo/SystemTest.scala => false
unit: should include file:/Users/patric/Dropbox/tmp/sbt/src/test/scala/com/springer/core/unit/foo/UnitTest.scala => true
[info] Compiling 2 Scala sources to /Users/patric/Dropbox/tmp/sbt/target/scala-2.10/test-classes...
[info] UnitTest:
[info] - should run a unit test
[info] Passed: : Total 1, Failed 0, Errors 0, Passed 1, Skipped 0
[success] Total time: 1 s, completed 09-Oct-2013 17:15:24
> integration:test
integration: should include file:/Users/patric/Dropbox/tmp/sbt/src/test/scala/com/springer/core/functional/foo/FunctionalTest.scala => false
integration: should include file:/Users/patric/Dropbox/tmp/sbt/src/test/scala/com/springer/core/integration/foo/IntegrationTest.scala => true
integration: should include file:/Users/patric/Dropbox/tmp/sbt/src/test/scala/com/springer/core/shared/utils/Clock.scala => true
integration: should include file:/Users/patric/Dropbox/tmp/sbt/src/test/scala/com/springer/core/system/foo/SystemTest.scala => false
integration: should include file:/Users/patric/Dropbox/tmp/sbt/src/test/scala/com/springer/core/unit/foo/UnitTest.scala => false
unit: should include file:/Users/patric/Dropbox/tmp/sbt/src/test/scala/com/springer/core/functional/foo/FunctionalTest.scala => false
unit: should include file:/Users/patric/Dropbox/tmp/sbt/src/test/scala/com/springer/core/integration/foo/IntegrationTest.scala => false
unit: should include file:/Users/patric/Dropbox/tmp/sbt/src/test/scala/com/springer/core/shared/utils/Clock.scala => true
unit: should include file:/Users/patric/Dropbox/tmp/sbt/src/test/scala/com/springer/core/system/foo/SystemTest.scala => false
unit: should include file:/Users/patric/Dropbox/tmp/sbt/src/test/scala/com/springer/core/unit/foo/UnitTest.scala => true
[info] Compiling 2 Scala sources to /Users/patric/Dropbox/tmp/sbt/target/scala-2.10/test-classes...
[info] Compiling 2 Scala sources to /Users/patric/Dropbox/tmp/sbt/target/scala-2.10/test-classes...
[info] UnitTest:
[info] - should run a unit test
[info] Passed: : Total 1, Failed 0, Errors 0, Passed 1, Skipped 0
[success] Total time: 2 s, completed 09-Oct-2013 17:15:30