fix unit test categorization

Before this change, tests for 'ensure' values other than 'present' are
nested under 'when with an ensure of present', resulting in:

Puppet::Type::Vcsrepo::ProviderGit
  when with an ensure of present
    when with an ensure of present - with a revision that is a remote branch
      executes 'git clone' and 'git checkout -b'
[...]
    when with an ensure of bare - with revision
      raises an error
    when with an ensure of bare - without revision
      justs execute 'git clone --bare'
    when with an ensure of bare - without a source
      executes 'git init --bare'
    when with an ensure of mirror - with revision
      raises an error
    when with an ensure of mirror - without revision
      justs execute 'git clone --mirror'
    when with an ensure of mirror - without a source
      raises an exeption
    when with an ensure of mirror - with multiple remotes
      executes 'git clone --mirror' and set all remotes to mirror

Author: bugfood

spec/unit/puppet/provider/vcsrepo/git_spec.rb

@@ -171,7 +171,9 @@ def branch_a_list(include_branch = nil?)
         provider.create
       end
     end
+  end
 
+  context 'when with an ensure of bare' do
     context 'when with an ensure of bare - with revision' do
       it 'raises an error' do
         resource[:ensure] = :bare
@@ -202,7 +204,9 @@ def branch_a_list(include_branch = nil?)
         provider.create
       end
     end
+  end
 
+  context 'when with an ensure of mirror' do
     context 'when with an ensure of mirror - with revision' do
       it 'raises an error' do
         resource[:ensure] = :mirror