Arcyd: fix abdt_fs checks for dirty index
Arcyd: fix abdt_fs checks for dirty index

Raise Error classes instead of printing them when the index is
unexpectedly dirty in Accessor.

Test Plan:
$ ./precommit.sh
$ ./testbed/arcyd/test_shell.sh

    # try to remove a repo when index is dirty
    $ cd ../arcyd
    $ arcyd stop
    $ touch blah && git add blah
    $ arcyd rm-repo localhost_fs1_origin
    .. dirty index error ..

    # try to remove a repo when index is clean
    $ git reset
    $ arcyd rm-repo localhost_fs1_origin
    .. ok ..

    # try to add a repo when index is dirty
    $ touch blah && git add blah
    $ arcyd add-repo localhost fs1 origin
    .. dirty index error ..

    # try to add a repo when index is clean
    $ git reset
    $ arcyd add-repo localhost fs1 origin
    .. ok ..

bloomberg/phabricator-tools,kjedruczyk/phabricator-tools,kjedruczyk/phabricator-tools,cs-shadow/phabricator-tools,kjedruczyk/phabricator-tools,bloomberg/phabricator-tools,bloomberg/phabricator-tools,aevri/phabricator-tools,aevri/phabricator-tools,kjedruczyk/phabricator-tools,aevri/phabricator-tools,bloomberg/phabricator-tools,cs-shadow/phabricator-tools,aevri/phabricator-tools,bloomberg/phabricator-tools,aevri/phabricator-tools,kjedruczyk/phabricator-tools,cs-shadow/phabricator-tools,cs-shadow/phabricator-tools,cs-shadow/phabricator-tools