Skip 'thor' loading if it is already loaded
Display warning if graphviz gem is not installed. Fixes #2435
load graphviz gem before rubygems is unloaded
gem list -i omg who knew
stop suppressing GitError while loading specs

for detail on caught PathErrors, use --verbose

fixes #2461
subcommands have man pages, too
Fixed typos
Adds missing method to Bundler::UI
Don't mutate the gem method options hash

fixes #2447
Update ISSUES.md with correct link to bundle man page
Add spec for exitstatus for unrecognized tasks
Set THOR_DEBUG flag

Enable debug flag so errors from Thor are getting raised. This enables
us to rescue them, inform the user and exit with a failing exit code.
Rescue thor errors

Since debug flag is set thor raises errors. Rescue the error and print
the message to the ui. Then exit with a failing exit code.
When a command is unknown exit with 15

Treat unknown command the same as invalid option.
Exit code 15 is used when an option is invalid. Tread unk
Merge pull request #2478 from pjvds/fail_for_unknown_commands

Fix succeeding error code on Thor failures

Commits were cherry-picked into a new branch and then merged into 1-3-stable,
because the original source branch was out of date.

Fixes #2478
Display the Gem::SystemExitException if there is a rubygems
configuration problem
clean up gem error printing
Correct Thor error name
Revert "refresh so that `bundle exec bundle -v` works again"

This reverts commit 7b748268997d7522c1b3507b52ce61e7716b2e42, and thus
fixes #2454.

The refresh doesn't seem to be necessary... though the original commit
was a bit vague on exactly what it was setting out to fix.
Fix #2502