bug: Misleading error message when no successors available

[joelanford]

I have a scenario setup with 6.0.1 installed, where I updated the spec.version to 6.0.0 with upgrade policy enforcement enabled.

I got the following error message:

    message: 'error upgrading from currently installed version "6.0.1": no package
      "cockroachdb" matching version "6.0.0" found'

This makes it sound like:

• there just isn't a 6.0.0 version in the catalog
• if there was a 6.0.0 version (there is), the upgrade would proceed (it doesn't, because 6.0.0 is not a successor)

I expected something along the lines of (where the list of best available successors would be sugar on top):

    message: 'error upgrading from currently installed version "6.0.1": desired package "cockroachdb" with version range "6.0.0" does not match any successor of "6.0.1", which include "6.0.3" (highest-available z-update) and "6.4.0" (highest available y-update)

[itroyano]

/assign

[dhoover103]

/assign

[joelanford]

@itroyano and @dhoover103, I'm refactoring this area of code in #1033, so you may want to hold off or branch off of that PR.

[LalatenduMohanty]

@joelanford mentioned that he has already fixed it, so assigning it to him to cross check.