fix branch handling and auto-detection

.github/workflows/test.yml

@@ -21,15 +21,21 @@ jobs:
         pip install . mypy pytest black
     - name: Test
       run: make test-melpazoid
+
     - name: Test 'shx' Pull Request  # a small package with few dependencies
-      env:  # ... which already exists on MELPA:
-        EXIST_OK: true
+      env:  
+        CI_BRANCH: master  # always build the master branch for this repo
+        EXIST_OK: true     # we expect that it already exists on MELPA
       run: MELPA_PR_URL=https://github.com/melpa/melpa/pull/4749 make
+
     - name: Test 'kanban' Recipe  # notably this is a Mercurial recipe
-      env:  # ...and we expect it to have some nags:
-        EXPECT_ERROR: 2
+      env:  
+        CI_BRANCH: default # always build the default branch on this repo
+        EXPECT_ERROR: 2    # we expect it to have some nags
       run: RECIPE='(kanban :fetcher hg :url "https://hg.sr.ht/~arnebab/kanban.el")' make
+
     - name: Test 'magit' Recipe  # magit is a large recipe
-      env:  # ...which may have a couple of nags:
-        EXPECT_ERROR: 2
+      env:
+        CI_BRANCH: master  # always build the master branch on this repo
+        EXPECT_ERROR: 2    # we expect it to have some nags
       run: RECIPE='(magit :fetcher github :repo "magit/magit" :files ("lisp/magit" "lisp/magit*.el" "lisp/git-rebase.el" "Documentation/magit.texi" "Documentation/AUTHORS.md" "LICENSE" (:exclude "lisp/magit-libgit.el")))' make

melpazoid/melpazoid.py

@@ -613,14 +613,14 @@ def _clone(repo: str, into: str, branch: str, fetcher: str = 'github') -> bool:
 
     # check if we're being used in GitHub CI -- if so, modify the branch
     if not branch and 'RECIPE' in os.environ:
-        os.path.split(os.environ.get('GITHUB_REF', ''))
-        branch = os.path.split(os.environ.get('GITHUB_REF', ''))[-1]
-        if not branch:
-            branch = os.environ.get('TRAVIS_PULL_REQUEST_BRANCH', '')
-        if not branch:
-            branch = os.environ.get('TRAVIS_BRANCH', '')
+        branch = (
+            os.environ.get('CI_BRANCH', '')
+            or os.path.split(os.environ.get('GITHUB_REF', ''))[-1]
+            or os.environ.get('TRAVIS_PULL_REQUEST_BRANCH', '')
+            or os.environ.get('TRAVIS_BRANCH', '')
+        )
         if branch:
-            _note(f"CI workflow detected; defaulting to branch '{branch}'", CLR_INFO)
+            _note(f"CI workflow detected; using branch '{branch}'", CLR_INFO)
 
     scm = 'hg' if fetcher == 'hg' else 'git'
     if not requests.get(repo).ok:
@@ -636,7 +636,7 @@ def _clone(repo: str, into: str, branch: str, fetcher: str = 'github') -> bool:
         if fetcher in {'github', 'gitlab', 'bitbucket'}:
             options += ['--depth', '1']
     elif scm == 'hg':
-        options = ['--branch', branch] if branch else []
+        options = ['--branch', branch if branch else 'default']
     else:
         _fail(f"Unrecognized SCM: {scm}")
         return False