```ruby
module Rubycritic
  module SourceControlSystem

    class Git < Base
      register_system

      def self.supported?
        `git branch 2>&1` && $?.success?
      end

      def self.to_s
        "Git"
      end

      def has_revision?
        head_reference && $?.success?
      end

      def head_reference
        `git rev-parse --verify HEAD`.chomp
      end

      def travel_to_head
        stash_successful = stash_changes
        yield
      ensure
        travel_to_original_state if stash_successful
      end

      def revisions_count(path)
        `git log --follow --format=oneline #{path.shellescape}`.count("\n")
      end

      def date_of_last_commit(path)
        `git log -1 --date=iso --format=%ad #{path.shellescape}`.chomp!
      end

      private

      def stash_changes
        return false if everything_commmited?

        stashes_count_before = stashes_count
        `git stash`
        stashes_count_after = stashes_count
        stashes_count_after > stashes_count_before
      end

      def everything_commmited?
        `git status --porcelain`.empty?
      end

      def stashes_count
        `git stash list`.count("\n")
      end

      def travel_to_original_state
        `git stash pop`
      end
    end

  end
end
```

Modify string in place with bang method
user
```ruby
module Rubycritic
  module SourceControlSystem

    class Git < Base
      register_system

      def self.supported?
        `git branch 2>&1` && $?.success?
      end

      def self.to_s
        "Git"
      end

      def has_revision?
        head_reference && $?.success?
      end

      def head_reference
        `git rev-parse --verify HEAD`.chomp!
      end

      def travel_to_head
        stash_successful = stash_changes
        yield
      ensure
        travel_to_original_state if stash_successful
      end

      def revisions_count(path)
        `git log --follow --format=oneline #{path.shellescape}`.count("\n")
      end

      def date_of_last_commit(path)
        `git log -1 --date=iso --format=%ad #{path.shellescape}`.chomp!
      end

      private

      def stash_changes
        return false if everything_commmited?

        stashes_count_before = stashes_count
        `git stash`
        stashes_count_after = stashes_count
        stashes_count_after > stashes_count_before
      end

      def everything_commmited?
        `git status --porcelain`.empty?
      end

      def stashes_count
        `git stash list`.count("\n")
      end

      def travel_to_original_state
        `git stash pop`
      end
    end

  end
end
```
assistant