Strip trailing / or \ when rolling.
Strip trailing / or \ when rolling.

Otherwise it makes CL description like foo/bar// which is ugly.

R=vadimsh@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1468183002

git-svn-id: fd409f4bdeea2bb50a5d34bb4d4bfc2046a5a3dd@297670 0039d316-1c4b-4281-b951-d872f2087c98

duanwujie/depot_tools,hsharsha/depot_tools,duanwujie/depot_tools,primiano/depot_tools,hsharsha/depot_tools,azureplus/chromium_depot_tools,hsharsha/depot_tools,duanwujie/depot_tools,duongbaoduy/gtools,primiano/depot_tools,duongbaoduy/gtools,disigma/depot_tools,CoherentLabs/depot_tools,aleonliao/depot_tools,azureplus/chromium_depot_tools,disigma/depot_tools,aleonliao/depot_tools,primiano/depot_tools,CoherentLabs/depot_tools,azureplus/chromium_depot_tools,disigma/depot_tools,aleonliao/depot_tools,duongbaoduy/gtools