Support for tags

[pomek]

🎯 Goals

• The goal is to allow checking out a repository to a tag (version) instead of a branch.
• The tag can be unknown, so we want to check out the latest created.

📗 Story

• Given: I am a developer who uses the https://github.com/ckeditor/ckeditor5-dev repository in a project.

   {
     "packages": "external/",
     "dependencies": {
       "ckeditor5-dev": "ckeditor/ckeditor5-dev@latest"
     }
   }

• When: I execute mrgit sync.
• Then: The tool checks out the ckeditor5-dev repository on the v31.1.11 tag.

💡 Hints

• When creating the issue, the latest version in ckeditor5-dev is v31.1.11
  
• We should also support defining a particular tag: "ckeditor5-dev": "ckeditor/ckeditor5-dev@v31.0.0".
• The @latest has a specific meaning - find the latest tag name and use it.

[przemyslaw-zan]

Branch.

Support for using tags while cloning the repository is almost complete. For whatever reason, calling:

LATEST=$( git describe --abbrev=0 --tags ) && git checkout --quiet $LATEST

Works fine locally, but when trying to do it via script, it throws an error:

'LATEST' is not recognized as an internal or external command, operable program or batch file.

After I fix this, I will also have to implement this functionality for updating the repository, not just cloning it.

Question: Is it okay for the checked out tag to be in a detached head state? [Edit] It is ok.

[przemyslaw-zan]

Separate syntax for tags and branches could be benefitial for clarity while defining configuration in the mrgit.json file.

• branches - #: organization/repository#release
• tags - @: organization/repository@latest

However, while I can ensure that anything following @ is a tag by using the tags/ prefix while checking out, there is no way that I found to ensure that # is always followed by a branch. This means, that #v30.0.0 is technically a valid syntax, even though it should not be.

[pomek]

That makes sense. We could detect if a tag is specified with the branch symbol, but I guess it is not worth it. So, when passing both: #v35.0.0 and @35.0.0 as a suffix, the application should accept them. When passing @latest, it tries to check out the latest tag. But passing #latest is about checking out a branch.

[przemyslaw-zan]

Should we assume that tags should always contain semantic version number with possibility of additional characters, (eg. @v35.0.0) or should we allow any tag name? (eg. @tagname)?

@latest is a separate case, so I'm assking about other cases.