Warning messages when trying to deploy

This actually prevents me from deploying.

```bash
cap production deploy
Skipping task `rbenv:update_ruby_build'.
Skipping task `rbenv:update_ruby_build'.
Capistrano tasks may only be invoked once. Since task `rbenv:update_ruby_build' was previously invoked, invoke("rbenv:update_ruby_build") at /home/lloyd/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/capistrano-rbenv-install-1.2.0/lib/capistrano/tasks/rbenv_install.rake:44 will be skipped.
Skipping task `rbenv:update_ruby_build'.
Capistrano tasks may only be invoked once. Since task `rbenv:update_ruby_build' was previously invoked, invoke("rbenv:update_ruby_build") at /home/lloyd/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/capistrano-rbenv-install-1.2.0/lib/capistrano/tasks/rbenv_install.rake:44 will be skipped.
If you really meant to run this task again, use invoke!("rbenv:update_ruby_build")
THIS BEHAVIOR MAY CHANGE IN A FUTURE VERSION OF CAPISTRANO. Please join the conversation here if this affects you.
https://github.com/capistrano/capistrano/issues/1686
Capistrano tasks may only be invoked once. Since task `rbenv:update_ruby_build' was previously invoked, invoke("rbenv:update_ruby_build") at /home/lloyd/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/capistrano-rbenv-install-1.2.0/lib/capistrano/tasks/rbenv_install.rake:44 will be skipped.
If you really meant to run this task again, use invoke!("rbenv:update_ruby_build")
If you really meant to run this task again, use invoke!("rbenv:update_ruby_build")
THIS BEHAVIOR MAY CHANGE IN A FUTURE VERSION OF CAPISTRANO. Please join the conversation here if this affects you.
THIS BEHAVIOR MAY CHANGE IN A FUTURE VERSION OF CAPISTRANO. Please join the conversation here if this affects you.
Skipping task `rbenv:update_ruby_build'.
```

If I make the above change I then am unable to deploy due to a git error:

```bash
00:00 rbenv:update_ruby_build
01 git pull
01 error: Your local changes to the following files would be overwritten by merge:
01 bin/ruby-build
01 test/build.bats
01 Please commit your changes or stash them before you merge.
01 Aborting
01 Updating 37d7143..75c2fe4
# terminated with exception (report_on_exception is true):
Traceback (most recent call last):
11: from /home/lloyd/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/sshkit-1.21.2/lib/sshkit/runners/parallel.rb:12:in `block (2 levels) in execute'
10: from /home/lloyd/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/sshkit-1.21.2/lib/sshkit/backends/abstract.rb:31:in `run'

Start with the deploy output and the rbenv:update_ruby_build task referenced at rbenv_install.rake:44. Inspect the reported bin/ruby-build and test/build.bats changes, then reproduce the deployment and trace where the repeated task invocation and git pull failure occur. Done means the reported deployment path no longer emits the repeated warnings or fails on those local changes.

Written by the indexing model from the issue text.