repo: update to 2.8 launcher

Bug: None
Test: `repo sync` still works
Change-Id: Idfd893d3e7a81a4a2526eb61b9d45641988c32c0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2212957
Reviewed-by: Sean McAllister <smcallis@google.com>
Commit-Queue: Mike Frysinger <vapier@chromium.org>

repo

@@ -133,7 +133,7 @@ if not REPO_REV:
   REPO_REV = 'stable'
 
 # increment this whenever we make important changes to this script
-VERSION = (2, 5)
+VERSION = (2, 8)
 
 # increment this if the MAINTAINER_KEYS block is modified
 KEYRING_VERSION = (2, 3)
@@ -317,9 +317,11 @@ def GetParser(gitc_init=False):
                    help='restrict manifest projects to ones with a specified '
                         'platform group [auto|all|none|linux|darwin|...]',
                    metavar='PLATFORM')
+  group.add_option('--clone-bundle', action='store_true',
+                   help='enable use of /clone.bundle on HTTP/HTTPS (default if not --partial-clone)')
   group.add_option('--no-clone-bundle',
-                   dest='clone_bundle', default=True, action='store_false',
-                   help='disable use of /clone.bundle on HTTP/HTTPS')
+                   dest='clone_bundle', action='store_false',
+                   help='disable use of /clone.bundle on HTTP/HTTPS (default if --partial-clone)')
   group.add_option('--no-tags',
                    dest='tags', default=True, action='store_false',
                    help="don't fetch tags in the manifest")
@@ -502,6 +504,9 @@ def _Init(args, gitc_init=False):
   opt.quiet = opt.output_mode is False
   opt.verbose = opt.output_mode is True
 
+  if opt.clone_bundle is None:
+    opt.clone_bundle = False if opt.partial_clone else True
+
   url = opt.repo_url or REPO_URL
   rev = opt.repo_rev or REPO_REV
 
@@ -1169,6 +1174,10 @@ def main(orig_args):
   if my_main:
     repo_main = my_main
 
+  if not repo_main:
+    print("fatal: unable to find repo entry point", file=sys.stderr)
+    sys.exit(1)
+
   ver_str = '.'.join(map(str, VERSION))
   me = [sys.executable, repo_main,
         '--repo-dir=%s' % rel_repo_dir,