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

command.py

@@ -136,7 +136,7 @@ class Command(object):
 
     groups = mp.config.GetString('manifest.groups')
     if not groups:
-      groups = 'all,-notdefault,platform-' + platform.system().lower()
+      groups = 'default,platform-' + platform.system().lower()
     groups = [x for x in re.split(r'[,\s]+', groups) if x]
 
     if not args:

project.py

@@ -672,9 +672,14 @@ class Project(object):
        project_groups: "all,group1,group2"
        manifest_groups: "-group1,group2"
        the project will be matched.
+
+       The special manifest group "default" will match any project that
+       does not have the special project group "notdefault"
     """
-    expanded_manifest_groups = manifest_groups or ['all', '-notdefault']
+    expanded_manifest_groups = manifest_groups or ['default']
     expanded_project_groups = ['all'] + (self.groups or [])
+    if not 'notdefault' in expanded_project_groups:
+      expanded_project_groups += ['default']
 
     matched = False
     for group in expanded_manifest_groups:

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",

subcmds/init.py

@@ -91,8 +91,9 @@ to update the working directory files.
                  dest='depth',
                  help='create a shallow clone with given depth; see git clone')
     g.add_option('-g', '--groups',
-                 dest='groups', default='all,-notdefault',
-                 help='restrict manifest projects to ones with a specified group',
+                 dest='groups', default='default',
+                 help='restrict manifest projects to ones with specified '
+                      'group(s) [default|all|G1,G2,G3|G4,-G5,-G6]',
                  metavar='GROUP')
     g.add_option('-p', '--platform',
                  dest='platform', default='auto',
@@ -169,7 +170,7 @@ to update the working directory files.
 
     groups = [x for x in groups if x]
     groupstr = ','.join(groups)
-    if opt.platform == 'auto' and groupstr == 'all,-notdefault,platform-' + platform.system().lower():
+    if opt.platform == 'auto' and groupstr == 'default,platform-' + platform.system().lower():
       groupstr = None
     m.config.SetString('manifest.groups', groupstr)