Use py2.6 compatible syntax in remote_try unittest.
Use py2.6 compatible syntax in remote_try unittest.

BUG=chromium-os:31985
TEST=run the test

Change-Id: Ic13db39b064dc48fafdfddd950393ea226a0b839
Reviewed-on: https://gerrit.chromium.org/gerrit/25689
Reviewed-by: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>
Commit-Ready: Brian Harring <fdc2d0a2e2340b623587cee5ea8dff425d1eb1f3@chromium.org>
Tested-by: Brian Harring <fdc2d0a2e2340b623587cee5ea8dff425d1eb1f3@chromium.org>

bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite,zhang0137/chromite,coreos/chromite,zhang0137/chromite,zhang0137/chromite,bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite,coreos/chromite,coreos/chromite,chadversary/chromiumos.chromite