Initial clone must be from a branch

[holmboe]

Using this .sgit.yml:

repos:
  tag-major-minor:
    clone-url: git@gitlab.com:dynamist/subgit-sample-f.git
    revision:
      tag: v1.2

Doing an initial sgit update, I get:

$ sgit update
DEBUG: Repo update - all
Are you sure you want to update the following repos "tag-major-minor"
(y/n) << y
Traceback (most recent call last):
  File "/home/nn/code/dynamist/sgit/sgit/cli.py", line 186, in cli_entrypoint
    exit_code = run(cli_args, sub_args)
  File "/home/nn/code/dynamist/sgit/sgit/cli.py", line 172, in run
    retcode = core.update(repo)
  File "/home/nn/code/dynamist/sgit/sgit/core.py", line 297, in update
    raise SgitException('Initial clone must be from a branch')
sgit.exceptions.SgitException: Initial clone must be from a branch
> /home/nn/code/dynamist/sgit/sgit/core.py(297)update()
-> raise SgitException('Initial clone must be from a branch')
(Pdb)