add an alias to option -d/--download as -e/--existing

[Waldir Pimenta]

The -d/--download option is somewhat ambiguous. According to the current code at
https://github.com/openstack-infra/git-review/blob/ddcfafda07eff0e8a8acd64d7ae144011fd90e69/git-review#L853
that option is supposed to "download the contents of an existing gerrit review into a branch".

I think that typing "git review --existing 1234" is much more explicit about what the command does. I do realize, of course, that a breaking change such as renaming an option isn't likely feasible at this point, so instead I suggest this to be implemented as an alias, along with a change in the documentation to not mention -d as a supported option, but rather have a note in the -e option's documentation saying something like "(older versions used -d for this purpose)".

[Cedric Brandily (cbrandily)]

OpenStack users seem to be used to the -d option

==> Won't Fix ?

[Waldir Pimenta (waldyrious)]

"OpenStack users seem to be used to the -d option" -- how could they *not* be? that's the only choice currently available...

Note that I'm not suggesting renaming the option, merely providing an alias. That way no current users will be inconvenienced, and new users will have an easier time remembering this option.

[Cedric Brandily (cbrandily)]

-d/--download refers to what it does "downloading" a change (in opposition to uploading) like --compare to compate .. --existing seems more like a existence check