tree 1b69c9bd802b179e07483a6ac60140cc13a6270c
parent de109c5b35cb8828fe81a7fb8661ce044d4ba007
author James Tucker <raggi@google.com> 1548411207 -0800
committer CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org> 1548476285 +0000

[images] faster incremental blob publishing

copytree was only used to produce the blob output directory. The blob output
directory is content addressed, as such repeating writes to target locations
is not useful work. The code for copytree is used to produce a copy-only-once
behavior that significantly reduces total number and cost of io operations
for incremental builds.

Change-Id: Idc4b14b88326f93cfe2ff5c43e01a6628f7b2bec