removed duplicate key assignment in dictionary

Remove second assignment to 'text' key. It seems that
buildbot.status.builder.BuildStatus.getText() always
returns a list of strings, so the first assignment:

  'text': " ".join(build.getText()),

should be sufficient.

This fixes 'duplicate-key (W0109)' pylint warning.
enable duplicate-key (W0109) pylint check
Merge branch 'pylint-duplicate-key' of git://github.com/elmirjagudin/buildbot