Add 'repo sync -d' to detach projects from their current topic

The -d flag moves the project back to a detached HEAD state,
matching what is listed in the manifest.  This can be useful to
set a client to something stable (or at least well-known), such as
before a sequence of 'repo download' commands are used to get some
changes for testing.

Signed-off-by: Shawn O. Pearce <sop@google.com>
2 files changed