List pull requests again

[vermiculus]

#1232 mentions the need for a command to list out pull requests (taken away by 8563e67, probably for semantic reasons), but I thought I'd reiterate the need here.

Related to vermiculus/magithub#44.

[akshatgoel]

@mislav I am looking to work on this issue. Here is my current understanding of the issue:
Currently hub only has command pull-request to create a PR but not list them. We should be able to list PRs as we do with issues right now (as added by the commit 8563e67).

Proposal:
I am thinking of moving current pull-request behavior to sub-command create to maintain parity with issue as well as to make listing (which is stateless operation compared to create) as default.

What do you think?

[mislav]

@akshatgoel That's a good plan. How do you envision this command and its subcommands to be called?

[timja]

Alternatively hub ls pull-request?

[vermiculus]

Even if there could be an option to skip this section of code, that would be sufficient:

for _, issue := range issues {
	if issue.PullRequest != nil {
		continue
	}
	ui.Printf(formatIssue(issue, flagIssueFormat, colorize))
}

[vermiculus]

@mislav If such a flag was added this week, do you have an estimate on when the change would make it into a release?

In other words, any idea when 2.3.0-pre9 will be tagged?

[mislav]

I could tag another prerelease after that. Thank you!