add a -n/--dry-run to the new fetch command in depot_tools

add a -n/--dry-run to the new fetch command in depot_tools

This is done as a hack since we don't really have real option parsing :(.

R=iannucci@chromium.org, agable@chromium.org, maruel@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=192154

[agable, 2013-04-03 21:06:59]

LGTM

https://codereview.chromium.org/13586004/diff/1/fetch.py
File fetch.py (right):

https://codereview.chromium.org/13586004/diff/1/fetch.py#newcode165
fetch.py:165: argv.pop(1)
This is the best way to do it for now.

I'll look into using optparse to get -h, -n, and their long equivalents while
passing any remaining args/options onto the current parser. That'll go in v2.

[Dirk Pranke, 2013-04-03 21:09:11]

Committed patchset #1 manually as r192154.