Suggestion: error "tag ... already exists" should distinguish between tagging different or same commit:

[M Hickford <mirth.hickford@xxxxxxxxx>]

Hi. Presently, the error "tag ... already exists" doesn't distinguish
between tagging the same commit or a different commit:

     >git tag hello v1.9.5

     >git tag hello v1.9.5
     fatal: tag 'hello' already exists

     >git tag hello v2.0.0
     fatal: tag 'hello' already exists

To inform the user, it would be nice to distinguish these cases, perhaps:

     >git tag hello v1.9.5
     fatal: tag 'hello' already exists pointing at
d4e6038a068d0aecd5ec28c83afbfc6d4903092f

     >git tag hello v2.0.0
     fatal: tag 'hello' already exists but points at
18a07354e33f86c8349ffdc300d9087876658264

The second error is typically more concerning than the first.

What do you think?