Print debugging information when svn info didn't return the URL

Right now, it'd simply crash with a KeyError.

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BUG=
TEST=


Review URL: http://codereview.chromium.org/8020004

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@102496 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed