[datahopper] Fix time range for loading Swarming tasks.
[datahopper] Fix time range for loading Swarming tasks.

Bug: skia:
Change-Id: I3f570d801dabbbdcbd6179c1cb4aacb0a012179c
Reviewed-on: https://skia-review.googlesource.com/18483
Reviewed-by: Eric Boren <0e499112533c8544f0505ea0d08394fb5ad7d8fa@google.com>
Commit-Queue: Ben Wagner <3ef7217be91069877d94f7907ce5479000772cd3@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot