Wrong rerun message when a test fails before the setup phase

[ekouts]

When a test fails before the setup phase (for example when it fails because of failed dependencies), the rerun message is wrong because the partition hasn't been set yet. -n T9 -p None --system generic would filter T9 in this example:

$ ./bin/reframe -c unittests/resources/checks_unlisted/deps_complex.py -r
[ReFrame Setup]
  version:           3.2-dev2 (rev: 3c8f324a)
  command:           './bin/reframe -c unittests/resources/checks_unlisted/deps_complex.py -r'

...

------------------------------------------------------------------------------
FAILURE INFO for T9 
  * Test Description: T9
  * System partition: generic
  * Environment: None
  * Stage directory: None
  * Node list: None
  * Job type: batch job (id=None)
  * Maintainers: []
  * Failing phase: startup
  * Rerun with '-n T9 -p None --system generic'
  * Reason: task dependency error: dependencies failed
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