Latest tag resolution seems to be broken for some projects
I have created a new tag (v0.3) in the nim-glfw project. Nimble can find the new tag when I use this command:

```
% nimble search nim-glfw --ver
...
nim-glfw:
  url:         https://github.com/ephja/nim-glfw (git)
  tags:        library, glfw, opengl, windowing, game
  description: A high-level GLFW 3 wrapper
  license:     MIT
  website:     https://github.com/ephja/nim-glfw
  versions:    0.2, v0.3, v0.21
```

Yet when I try to install the package, it insists on installing a previous version:

```
% nimble install nim-glfw
...
Downloading https://github.com/ephja/nim-glfw using git
  Verifying dependencies for glfw@0.2.1
 Installing glfw@0.2.1
    Prompt: glfw@0.2.1 already exists. Overwrite? [y/N]
    Answer: y
   Success: glfw installed successfully.
```

This doesn't make any sense to me, what is happening? I tried many stupid things over the last hour to no avail, I just cannot get it to work correctly...

Verbose mode doesn't give me any useful info either that would help troubleshooting the issue.