Fix Bitbucket branch and commit URLs

Bitbucket Cloud needs different paths than the shared defaults:

- Commits live at /commits/<sha>, not /commit/<sha> (the singular 404s).
- /src/<ref> 404s when the branch name contains a slash (e.g.
  release/9.12.x), because Bitbucket reads the first path segment as the
  ref. Browse via /src/HEAD/?at=<ref> with the slash percent-encoded;
  plain refs keep the simpler /src/<ref>.

Both changes are scoped to bitbucket.org, so GitHub, CodeCommit, and
Bitbucket Server are unaffected. Adds bats coverage for the commit URL
and the slash-branch source view.

git-open

@@ -199,7 +199,14 @@ else
 fi
 
 if [[ "$domain" == 'bitbucket.org' ]]; then
-  providerBranchRef="/src/$remote_ref"
+  # Bitbucket Cloud 404s on /src/<ref> when the branch name contains a slash: it reads the
+  # first path segment as the ref. Browse via HEAD and pass the real branch through ?at=
+  # (slashes percent-encoded); plain refs keep the simpler /src/<ref>.
+  if [[ "$remote_ref" == */* && -n "$branch" ]]; then
+    providerBranchRef="/src/HEAD/?at=${remote_ref//\//%2F}"
+  else
+    providerBranchRef="/src/$remote_ref"
+  fi
 elif [[ "${#pathargs[@]}" -ge 3 && ${pathargs[${#pathargs[@]} - 3]} == 'scm' ]]; then
   # Bitbucket server always has /scm/ as the third to last segment in the url path, e.g. /scm/ppp/test-repo.git
   # Anything before the 'scm' is part of the server's root context
@@ -269,7 +276,11 @@ openurl="$protocol://$domain/$urlpath"
 
 if (( is_commit )); then
     sha=$(git rev-parse HEAD)
-    openurl="$openurl/commit/$sha"
+    if [[ "$domain" == 'bitbucket.org' ]]; then
+      openurl="$openurl/commits/$sha"
+    else
+      openurl="$openurl/commit/$sha"
+    fi
 elif [[ $remote_ref != "master" || "$file" ]]; then
     # simplify URL for master
     openurl="$openurl$providerBranchRef"

test/git-open.bats

@@ -385,6 +385,13 @@ setup() {
   assert_output "https://bitbucket.org/paulirish/crbug-extension/src/mytag"
 }
 
+@test "bitbucket: commit" {
+  git remote set-url origin "git@bitbucket.org:paulirish/crbug-extension.git"
+  sha=$(git rev-parse HEAD)
+  run ../git-open "--commit"
+  assert_output "https://bitbucket.org/paulirish/crbug-extension/commits/${sha}"
+}
+
 @test "bitbucket: non-origin remote" {
   # https://github.com/paulirish/git-open/pull/4
   git remote add bbclone "git@bitbucket.org:rwhitbeck/git-open.git"
@@ -401,13 +408,14 @@ setup() {
   assert_output "https://bitbucket.org/kisom/consbri/src/devel"
 }
 
-@test "bitbucket: open source view with a slash/branch" {
+@test "bitbucket: slash branch source view via ?at=" {
   # https://github.com/paulirish/git-open/pull/26
   # see https://github.com/paulirish/git-open/issues/80 for feat/branchname issues
+  # /src/bugfix/conftest_fix 404s (Bitbucket reads 'bugfix' as the ref), so browse HEAD?at=<branch>
   git remote set-url origin "https://bitbucket.org/guyzmo/git-repo.git"
   git checkout -B "bugfix/conftest_fix"
   run ../git-open
-  assert_output "https://bitbucket.org/guyzmo/git-repo/src/bugfix/conftest_fix"
+  assert_output "https://bitbucket.org/guyzmo/git-repo/src/HEAD/?at=bugfix%2Fconftest_fix"
 }
 
 @test "bitbucket: ssh:// clone urls" {