Special handling for manifest group "default"

Change Details:
* Make "default" a special manifest group that matches any project that
  does not have the special project group "notdefault"
* Use "default" instead of "all,-notdefault" when user does not specify
  manifest group
* Expand -g option help to include example usage of manifest groups

Change Benefits:
* Allow a more intuitive and expressive manifest groups specification:
  * "default" instead of "all,-notdefault"
  * "default,foo" instead of "all,-notdefault,foo"
  * "default,-foo" instead of "all,-notdefault,-foo"
  * "foo,-default" which has no equivalent
* Default manifest groups behavior can be restored by the command
  'repo init -g default'. This is significantly more intuitive than the
  current equivalent command 'repo init -g all,-notdefault'.

Change-Id: I6d0673791d64a650110a917c248bcebb23b279d3

1 files changed, 2 insertions, 1 deletions

diff --git a/repo b/repo
index 6b374f72..c3484745 100755
--- a/repo
+++ b/repo
@@ -164,7 +164,8 @@ group.add_option('--depth', type='int', default=None,
                  help='create a shallow clone with given depth; see git clone')
 group.add_option('-g', '--groups',
                  dest='groups', default='default',
-                 help='restrict manifest projects to ones with a specified group',
+                 help='restrict manifest projects to ones with specified '
+                      'group(s) [default|all|G1,G2,G3|G4,-G5,-G6]',
                  metavar='GROUP')
 group.add_option('-p', '--platform',
                  dest='platform', default="auto",