Don't permit users to run repo status in a mirror client

If a client was created with "repo init --mirror" then there are
no working directories present, and no files checked out.  Using
a command like "repo status" in this context makes no sense, and
actually throws back a Pytyon traceback at the console when the
underlying commands fail out.

We now tag commands with the MirrorSafeCommand type if they are
able to be executed within a mirror directory safely.  Using a
command in a mirror which lacks this base class results in a
useful error letting you know the command isn't supported.

Bug: REPO-14
Signed-off-by: Shawn O. Pearce <sop@google.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/command.py b/command.py
index 516c2d9d..c3cad5ea 100644
--- a/command.py
+++ b/command.py
@@ -114,3 +114,8 @@ class PagedCommand(Command):
   """Command which defaults to output in a pager, as its
      display tends to be larger than one screen full.
   """
+
+class MirrorSafeCommand(object):
+  """Command permits itself to run within a mirror,
+     and does not require a working directory.
+  """