Fix handling of workflow branch

jupyter_releaser/lib.py

@@ -514,19 +514,24 @@ def prep_git(ref, branch, repo, auth, username, url):
     if not checkout_exists:
         util.run(f"git remote add origin {url}")
 
-    branch = branch or util.get_default_branch()
-    ref = ref or ""
-
     # Make sure we have *all* tags
     util.run(f"{util.GIT_FETCH_CMD} --tags --force")
 
     # Handle the ref
+    ref = ref or ""
     if ref.startswith("refs/pull/"):
         pull = ref[len("refs/pull/") :]
         ref_alias = f"refs/pull/{pull}"
+    elif ref.startswith("refs/heads/") and not branch:
+        branch = ref[len("refs/heads/") :]
+        util.run(f"git fetch origin {branch}")
+        ref = None
     else:
         ref = None
 
+    # Handle the branch.
+    branch = branch or util.get_default_branch()
+
     # Reuse existing branch if possible
     if ref:
         util.run(f"{util.GIT_FETCH_CMD} +{ref}:{ref_alias}")

tests/test_cli.py

@@ -60,6 +60,22 @@ def test_prep_git_tag(py_package, runner):
     assert util.get_branch() == tag, util.get_branch()
 
 
+def test_prep_git_ref_branch(py_package, runner):
+    branch = "ref-branch"
+    util.run(f"git checkout -b {branch} origin/foo")
+    result = runner(
+        ["prep-git", "--git-url", py_package],
+        env=dict(GITHUB_ACTIONS="", RH_REF=f"refs/heads/{branch}"),
+    )
+
+    log = get_log()
+    assert "before-prep-git" not in log
+    assert "after-prep-git" in log
+
+    os.chdir(util.CHECKOUT_NAME)
+    assert util.get_branch() == branch, util.get_branch()
+
+
 def test_prep_git_slashes(py_package, runner):
     branch = "a/b/c"
     util.run(f"git checkout -b {branch} foo")