Deleting keys deletes post-comment instead of pre-comment

[wwkimball]

Operating System

1. Name/Distribution: ANY
2. Version: ANY

Version of Python and packages in use at the time of the issue.

1. Distribution: ANY
2. Python Version: ANY Supported
3. Version of yamlpath installed: 3.6.4
4. Version of ruamel.yaml installed: ANY Supported

Minimum sample of YAML (or compatible) data necessary to trigger the issue

---
# test.yaml
key1: value1

# Pre-comment
remove_this: key

# Post-comment
keep_this: other key

Complete steps to reproduce the issue when triggered via:

1. yaml-set --delete --change=/remove_this test.yaml

Expected Outcome

---
# test.yaml
key1: value1

# Post-comment
keep_this: other key

Actual Outcome

---
# test.yaml
key1: value1

# Pre-comment
keep_this: other key

As you can see, the Pre-comment was preserved while both the post-comment and all whitespace after the target key was deleted.

Screenshot(s), if Available

[wwkimball]

This is a known issue with how ruamel.yaml handles comments (ca objects). Having said that, yamlpath should be able to compensate for this unexpected behavior.

[wwkimball]

The author of ruamel.yaml has indicated that I really should wait for the next release of his package before I tackle comment handling like this. Comments are complex, internal, and the API will be entirely unpredictable until he's done with his rewrite. So, for now, I'm shelving this.