librarian-puppet install --verbose fails if there is no git installed

[func0der]

Ran: > librarian-puppet install --verbose

Got:

default: [Librarian] Ruby Version: 2.3.3
    default: [Librarian] Ruby Platform: x86_64-linux-gnu
    default: [Librarian] Rubygems Version: 2.5.2.1
    default: [Librarian] Librarian Version: 0.6.4
    default: [Librarian] Librarian Adapter: puppet
    default: [Librarian] Librarian Adapter Version: 2.2.3
    default: [Librarian] Project: /vagrant
    default: [Librarian] Specfile: Puppetfile
    default: [Librarian] Lockfile: Puppetfile.lock
    default: cannot find git
    default: /var/lib/gems/2.3.0/gems/librarianp-0.6.4/lib/librarian/posix.rb:29:in `which!'
    default: /var/lib/gems/2.3.0/gems/librarianp-0.6.4/lib/librarian/source/git/repository.rb:20:in `bin'
    default: /var/lib/gems/2.3.0/gems/librarianp-0.6.4/lib/librarian/cli.rb:192:in `block in write_debug_header'
    default: /var/lib/gems/2.3.0/gems/librarianp-0.6.4/lib/librarian/logger.rb:37:in `block in debug'
    default: /var/lib/gems/2.3.0/gems/librarianp-0.6.4/lib/librarian/ui.rb:32:in `debug'
    default: /var/lib/gems/2.3.0/gems/librarianp-0.6.4/lib/librarian/logger.rb:37:in `debug'
    default: /var/lib/gems/2.3.0/gems/librarian-puppet-2.2.3/lib/librarian/puppet/util.rb:9:in `debug'
    default: /var/lib/gems/2.3.0/gems/librarianp-0.6.4/lib/librarian/cli.rb:192:in `write_debug_header'
    default: /var/lib/gems/2.3.0/gems/librarianp-0.6.4/lib/librarian/cli.rb:61:in `initialize'
    default: /var/lib/gems/2.3.0/gems/thor-0.20.0/lib/thor.rb:383:in `new'
    default: /var/lib/gems/2.3.0/gems/thor-0.20.0/lib/thor.rb:383:in `dispatch'
    default: /var/lib/gems/2.3.0/gems/thor-0.20.0/lib/thor/base.rb:466:in `start'
    default: /var/lib/gems/2.3.0/gems/librarianp-0.6.4/lib/librarian/cli.rb:26:in `block (2 levels) in bin!'
    default: /var/lib/gems/2.3.0/gems/librarianp-0.6.4/lib/librarian/cli.rb:31:in `returning_status'
    default: /var/lib/gems/2.3.0/gems/librarianp-0.6.4/lib/librarian/cli.rb:26:in `block in bin!'
    default: /var/lib/gems/2.3.0/gems/librarianp-0.6.4/lib/librarian/cli.rb:47:in `with_environment'
    default: /var/lib/gems/2.3.0/gems/librarianp-0.6.4/lib/librarian/cli.rb:26:in `bin!'
    default: /var/lib/gems/2.3.0/gems/librarian-puppet-2.2.3/bin/librarian-puppet:7:in `<top (required)>'
    default: /usr/local/bin/librarian-puppet:22:in `load'
    default: /usr/local/bin/librarian-puppet:22:in `<main>'

Seems: wrong.

Works with: librarian-puppet install.

Reason: Probably because you want to give information about the installed git environment in the verbose output.

Expected output: Do not require git to be actually installed until it is really needed.
Just show Not installed as the git environment state in the verbose output.

The script should only fail if git is really needed, in other words, if a module with a git background is defined in the Puppetfile