Add base/head/merge commit SHA information to `hub pr list`

commands/issue.go

@@ -413,6 +413,9 @@ func formatPullRequestPlaceholders(pr github.PullRequest) map[string]string {
 	return map[string]string{
 		"B":  base,
 		"H":  head,
+		"sB": pr.Base.Sha,
+		"sH": pr.Head.Sha,
+		"sm": pr.MergeCommitSha,
 		"rs": strings.Join(requestedReviewers, ", "),
 		"mD": mergedDate,
 		"mI": mergedAtISO8601,

commands/pr.go

@@ -67,8 +67,14 @@ pr checkout <PR-NUMBER> [<BRANCH>]
 
 		%B: base branch
 
+		%sB: base commit SHA
+
 		%H: head branch
 
+		%sH: head commit SHA
+
+		%sm: merge commit SHA
+
 		%au: login name of author
 
 		%as: comma-separated list of assignees

github/client.go

@@ -542,7 +542,8 @@ type Issue struct {
 	Head        *PullRequestSpec `json:"head"`
 	Base        *PullRequestSpec `json:"base"`
 
-	MaintainerCanModify bool `json:"maintainer_can_modify"`
+	MergeCommitSha      string `json:"merge_commit_sha"`
+	MaintainerCanModify bool   `json:"maintainer_can_modify"`
 
 	Comments  int          `json:"comments"`
 	Labels    []IssueLabel `json:"labels"`