openRepository opens remote branch tree urls by default

lib/github-file.coffee

@@ -79,8 +79,8 @@ class GitHubFile
   openRepository: ->
     @isOpenable().then (isOpenable) =>
       if isOpenable
-        @gitHubRepoUrl().then (gitHubRepoUrl) =>
-          @openUrlInBrowser(gitHubRepoUrl)
+        @treeUrl().then (treeUrl) =>
+          @openUrlInBrowser(treeUrl)
       else
         @reportValidationErrors()
 
@@ -170,6 +170,14 @@ class GitHubFile
       .then ([gitHubRepoUrl, branchName]) =>
         "#{gitHubRepoUrl}/compare/#{@encodeSegments(branchName)}"
 
+  treeUrl: ->
+    Promise.all([@gitHubRepoUrl(), @remoteBranchName()])
+      .then ([gitHubRepoUrl, remoteBranchName]) ->
+        if remoteBranchName isnt 'master'
+          "#{gitHubRepoUrl}/tree/#{remoteBranchName}"
+        else
+          gitHubRepoUrl
+
   encodeSegments: (segments='') ->
     segments = segments.split('/')
     segments = segments.map (segment) -> encodeURIComponent(segment)

spec/fixtures/some-branch.git/HEAD

@@ -0,0 +1 @@
+ref: refs/heads/some-branch

spec/fixtures/some-branch.git/config

@@ -0,0 +1,13 @@
+[core]
+	repositoryformatversion = 0
+	filemode = true
+	bare = false
+	logallrefupdates = true
+	ignorecase = true
+	precomposeunicode = false
+[remote "origin"]
+	url = https://github.com/some-user/some-repo.git
+	fetch = +refs/heads/*:refs/remotes/origin/*
+[branch "some-branch"]
+	remote = origin
+	merge = refs/heads/some-branch

spec/fixtures/some-branch.git/objects/80/b7897ceb6bd7531708509b50afeab36a4b73fd

@@ -0,0 +1 @@
+x
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spec/fixtures/some-branch.git/refs/heads/some-branch

@@ -0,0 +1 @@
+80b7897ceb6bd7531708509b50afeab36a4b73fd

spec/github-file-spec.coffee

@@ -375,6 +375,38 @@ describe "GitHubFile", ->
           runs -> expect(githubFile.openUrlInBrowser).toHaveBeenCalledWith \
             'https://github.com/some-user/some-repo'
 
+      describe "when the branch is not master", ->
+        fixtureName = 'some-branch'
+
+        beforeEach ->
+          setupWorkingDir(fixtureName)
+          setupGithubFile()
+
+        afterEach ->
+          teardownWorkingDirAndRestoreFixture(fixtureName)
+
+        it "opens the GitHub.com tree URL for the branch", ->
+          spyOn(githubFile, 'openUrlInBrowser')
+          waitsForPromise -> githubFile.openRepository()
+          runs -> expect(githubFile.openUrlInBrowser).toHaveBeenCalledWith \
+            'https://github.com/some-user/some-repo/tree/some-branch'
+
+      describe "when the local branch is not tracked", ->
+        fixtureName = 'non-tracked-branch'
+
+        beforeEach ->
+          setupWorkingDir(fixtureName)
+          setupGithubFile()
+
+        afterEach ->
+          teardownWorkingDirAndRestoreFixture(fixtureName)
+
+        it "opens the GitHub.com reposiotry URL", ->
+          spyOn(githubFile, 'openUrlInBrowser')
+          waitsForPromise -> githubFile.openRepository()
+          runs -> expect(githubFile.openUrlInBrowser).toHaveBeenCalledWith \
+            'https://github.com/some-user/some-repo'
+
     describe "openIssues", ->
       describe 'when the file is openable on GitHub.com', ->
         fixtureName = 'github-remote'