ui: don't show working tree if it is clean

[Suor]

Fixes #2386

[Suor]

Actually this is still wrong. Working tree might be clean but some .gitignored files changed.

[Suor]

So we can't know whether working tree is clean unless we check both git status and dvc status, which might make dvc metrics show <some-metric> considerably slower. The solution might be:

• perform the collection for both working tree and everything, then don't show if it's the same as current branch/head (will need to dup this in dvc status/dvc metrics show)
• let brancher know what we are looking for to limit dvc status to specific file(s)
• pass dirty=... to brancher by some code, which knows what we are looking for

All of those don't look too nice. Ideas?

[efiop]

So we can't know whether working tree is clean unless we check both git status and dvc status

@Suor Not sure I follow. If git is clean, then it means that there are no new files (untracked too, right?) in the repo. I don't quite understand why dvc status would matter there?

[Suor]

If metric is handled by dvc then it is in .gitignore, git will be clean, but metric might be changed, need to check that it corresponds to checksum.

[efiop]

@Suor Got it. Good one. And with dvc status, it would only need to be checked for the current branch once, right? Seems like it is not that bad, but it indeed might take some time for big directories. Limiting it to specific files (e.g. metrics) would only complicate it, and I'm not sure if it is worth it. Maybe the smartest thing here is to not overcomplicate this and leave it as is. Showing working tree is not that bad after all.

[Suor]

@efiop I am considering filtering output for metrics show, people usually have issue with that.

[efiop]

@Suor Feels weird to make brancher know about specific files that we want to check. Maybe

perform the collection for both working tree and everything, then don't show if it's the same as current branch/head (will need to dup this in dvc status/dvc metrics show)

Would be better? Btw, not sure why we need it for dvc status, as it doesn't care about branches really.

[Suor]

@efiop I thought dvc status --all-branches will show status for all branches or whatever. Looked at the code and realized those flags are simply ignored.

[Suor]

Closing in favor of #3025.