mirror: --preserve should not activate --overwrite

[vadmeste]

Community Contribution License

All community contributions in this pull request are licensed to the project maintainers under the terms of the Apache 2 license. By creating this pull request I represent that I have the right to license the contributions to the project maintainers under the Apache 2 license.

Description

Users would expect mirror will not override anything unless --overwrite flag is specified. However, currently --preserve will activate --overwrite, which is not needed. This commit will fix this behavior.

Motivation and Context

Fixing unexpected --preserve behavior

How to test this PR?

1. Mirror a folder to a bucket
2. Add few chars to a file inside the folder and run mirror again with --preserve flag

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Optimization (provides speedup with no functional changes)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [ ] Fixes a regression (If yes, please add commit-id or PR # here)
• [ ] Unit tests added/updated
• [ ] Internal documentation updated
• [ ] Create a documentation update request here

[harshavardhana]

Actually, there is a reason for that @vadmeste mc mirror --preserve means overwrite anything on the destination with the latest source. The approach should be that overwrite is allowed automatically if it sees differences since --preserve is meant to be for such scenarios like cp -a

[vadmeste]

My guess is that this is not intuitive and no one is using this already.