Reland 77470: Don't ignore first argument in TryChange

Reland 77470: Don't ignore first argument in TryChange

Original review: http://codereview.chromium.org/6650025/

BUG=none
TEST=`git try foo` gives a proper error message.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=78180

[Bernhard Bauer, 2011-03-14 19:11:42]

please review.

[M-A Ruel, 2011-03-14 19:46:45]

lgtm