Update migration needed

[vladshablinsky]

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew tests with your changes locally?

---

Description

# Formula#migration_needed?

def migration_needed?
  oldname && !rack.exist? && (dir = HOMEBREW_CELLAR/oldname).directory? &&
    !dir.subdirs.empty? && tap == Tab.for_keg(dir.subdirs.first).tap
end

Return false for each of those cases rather than chaining with && since It makes it much easier to follow.

#411 (comment)

cc @MikeMcQuaid

[MikeMcQuaid]

Might want to split the dir = out onto the previous line

[MikeMcQuaid]

👍 other than a few tweaks

[UniqMartin]

That's a tiny detail, but I think since this and the line above reference old_cellar_dir in their condition, it would be more logical to group them with the old_cellar_dir = line than with the line below, i.e. that's how I would expect the empty lines to be distributed:

return false unless oldname
return false if rack.exist?

old_cellar_dir = HOMEBREW_CELLAR/oldname
return false unless old_cellar_dir.directory?
return false if old_cellar_dir.subdirs.empty?

tap == Tab.for_keg(old_cellar_dir.subdirs.first).tap

Does that make sense?

[UniqMartin]

Two minor comments regarding distribution of empty lines and terminology, but otherwise 👍.

[MikeMcQuaid]

LGTM 👍

[UniqMartin]

I agree, hence the merge. The method is now much more readable. 👍

Merged in fbac41d. Thank you for another contribution to Homebrew, @vladshablinsky! 🎉