Fix `release` from detached HEAD

Don't try to default `target_commitish` to the currently checked out
branch. Instead, keep the value blank unless explicitly provided. It
will default to the main branch on the server.

commands/release.go

@@ -73,7 +73,8 @@ With '--include-drafts', include draft releases in the listing.
 		Further edit the contents of <FILE> in a text editor before submitting.
 
 	-c, --commitish <TARGET>
-		A SHA, tag, or branch name to attach the release to (default: current branch).
+		A commit SHA or branch name to attach the release to, only used if <TAG>
+		doesn't already exist (default: main branch).
 
 	<TAG>
 		The git tag name for this release.
@@ -272,13 +273,6 @@ func createRelease(cmd *Command, args *Args) {
 
 	gh := github.NewClient(project.Host)
 
-	commitish := flagReleaseCommitish
-	if commitish == "" {
-		currentBranch, err := localRepo.CurrentBranch()
-		utils.Check(err)
-		commitish = currentBranch.ShortName()
-	}
-
 	var title string
 	var body string
 	var editor *github.Editor
@@ -290,7 +284,7 @@ func createRelease(cmd *Command, args *Args) {
 		utils.Check(err)
 	} else {
 		cs := git.CommentChar()
-		message, err := renderReleaseTpl("Creating", cs, tagName, project.String(), commitish)
+		message, err := renderReleaseTpl("Creating", cs, tagName, project.String(), flagReleaseCommitish)
 		utils.Check(err)
 
 		editor, err := github.NewEditor("RELEASE", "release", message)
@@ -306,7 +300,7 @@ func createRelease(cmd *Command, args *Args) {
 
 	params := &github.Release{
 		TagName:         tagName,
-		TargetCommitish: commitish,
+		TargetCommitish: flagReleaseCommitish,
 		Name:            title,
 		Body:            body,
 		Draft:           flagReleaseDraft,

commands/release_tpl.go

@@ -6,7 +6,7 @@ import (
 )
 
 const releaseTmpl = `
-{{.CS}} {{.Operation}} release {{.TagName}} for {{.ProjectName}} from {{.BranchName}}
+{{.CS}} {{.Operation}} release {{.TagName}} for {{.ProjectName}}{{if .BranchName}} from {{.BranchName}}{{end}}
 {{.CS}}
 {{.CS}} Write a message for this release. The first block of
 {{.CS}} text is the title and the rest is the description.`

features/release.feature

@@ -181,7 +181,7 @@ MARKDOWN
       post('/repos/mislav/will_paginate/releases') {
         assert :draft => true,
                :tag_name => "v1.2.0",
-               :target_commitish => "master",
+               :target_commitish => "",
                :name => "will_paginate 1.2.0: Instant Gratification Monkey",
                :body => ""
 
@@ -195,6 +195,23 @@ MARKDOWN
       https://github.com/mislav/will_paginate/releases/v1.2.0\n
       """
 
+  Scenario: Create a release with target commitish
+    Given the GitHub API server:
+      """
+      post('/repos/mislav/will_paginate/releases') {
+        assert :tag_name => "v1.2.0",
+               :target_commitish => "my-branch"
+
+        status 201
+        json :html_url => "https://github.com/mislav/will_paginate/releases/v1.2.0"
+      }
+      """
+    When I successfully run `hub release create -m hello v1.2.0 -c my-branch`
+    Then the output should contain exactly:
+      """
+      https://github.com/mislav/will_paginate/releases/v1.2.0\n
+      """
+
   Scenario: Create a release with assets
     Given the GitHub API server:
       """