Default --pr-remote to Git's remote.pushDefault

README.md

@@ -23,7 +23,8 @@ options:
   -h, --help            show this help message and exit
   -V, --version         show program's version number and exit
   --dry-run             Prints out the commands, but not executed
-  --pr-remote REMOTE    Git remote to use for PR branches
+  --pr-remote REMOTE    Git remote to use for PR branches (default:
+                        remote.pushDefault or origin)
   --upstream-remote REMOTE
                         Git remote to use for upstream branches
   --abort               Abort current cherry-pick and clean up branch
@@ -89,9 +90,11 @@ $ git remote add upstream https://github.com/python/cpython.git
 ```
 
 By default, the PR branches used to submit pull requests back to the main
-repository are pushed to `origin`. If this is incorrect, then the correct
-remote will need be specified using the `--pr-remote` option (e.g.
-`--pr-remote pr` to use a remote named `pr`).
+repository are pushed to Git's `remote.pushDefault`, or `origin` if that is
+not set. To set it for a group of checkouts, use an
+[`includeIf`](https://git-scm.com/docs/git-config#_conditional_includes)
+in your global Git config. To use a remote named `pr`, either pass
+`--pr-remote pr` or set `remote.pushDefault` to `pr`.
 
 
 ## Cherry-picking 🐍🍒⛏️
@@ -122,7 +125,8 @@ Use the full commit hash for `cherry_picker.py`.
 
 ```
 --dry-run                 Dry Run Mode.  Prints out the commands, but not executed.
---pr-remote REMOTE        Specify the git remote to push into.  Default is 'origin'.
+--pr-remote REMOTE        Specify the git remote to push into.  Default is
+                          remote.pushDefault or 'origin'.
 --upstream-remote REMOTE  Specify the git remote to use for upstream branches.
                           Default is 'upstream' or 'origin' if the former doesn't exist.
 --status                  Do `git status` in cpython directory.

cherry_picker/cherry_picker.py

@@ -139,7 +139,7 @@ def __init__(
         if dry_run:
             print("Dry run requested, listing expected command sequence")
 
-        self.pr_remote = pr_remote
+        self.pr_remote = pr_remote or get_git_config_val("remote.pushDefault", "origin")
         self.upstream_remote = upstream_remote
         self.commit_sha1 = commit_sha1
         self.branches = branches
@@ -727,12 +727,8 @@ class state:
     def is_mirror(self) -> bool:
         """Return True if the current repository was created with --mirror."""
 
-        cmd = ["git", "config", "--local", "--get", "remote.origin.mirror"]
-        try:
-            out = self.run_cmd(cmd, required_real_result=True)
-        except subprocess.CalledProcessError:
-            return False
-        return out.startswith("true")
+        mirror = get_git_config_val("remote.origin.mirror", "", local=True)
+        return mirror.startswith("true")
 
 
 def get_parser():
@@ -751,8 +747,11 @@ def get_parser():
     parser.add_argument(
         "--pr-remote",
         metavar="REMOTE",
-        default="origin",
-        help="Git remote to use for PR branches",
+        default=None,
+        help=(
+            "Git remote to use for PR branches "
+            "(default: remote.pushDefault or origin)"
+        ),
     )
     parser.add_argument(
         "--upstream-remote",
@@ -1095,15 +1094,22 @@ def wipe_cfg_vals_from_git_cfg(*cfg_opts):
 def load_val_from_git_cfg(cfg_key_suffix):
     """Retrieve one option from Git config."""
     cfg_key = f'cherry-picker.{cfg_key_suffix.replace("_", "-")}'
-    cmd = "git", "config", "--local", "--get", cfg_key
+    return get_git_config_val(cfg_key, local=True)
+
+
+def get_git_config_val(key, default=None, *, local=False):
+    """Retrieve one option from Git config, or default if unset or empty."""
+    scope = ("--local",) if local else ()
+    cmd = "git", "config", *scope, "--get", key
     try:
-        return (
+        value = (
             subprocess.check_output(cmd, stderr=subprocess.DEVNULL)
             .strip()
             .decode("utf-8")
         )
     except subprocess.CalledProcessError:
-        return None
+        value = None
+    return value or default
 
 
 def from_git_rev_read(path):

cherry_picker/test_cherry_picker.py

@@ -25,6 +25,7 @@
     get_commits_from_backport_branch,
     get_current_branch,
     get_full_sha_from_short,
+    get_git_config_val,
     get_sha1_from,
     get_state,
     load_config,
@@ -317,6 +318,15 @@ def test_upstream_name(
     assert cp.upstream == remote_name
 
 
+@pytest.mark.parametrize(
+    "value,expected", ((None, "default"), ("", "default"), ("set", "set"))
+)
+def test_get_git_config_val(value, expected, tmp_git_repo_dir, git_config):
+    if value is not None:
+        git_config("--local", "cherry-picker.test-key", value)
+    assert get_git_config_val("cherry-picker.test-key", "default") == expected
+
+
 @pytest.mark.parametrize(
     "remote_to_add,remote_name,upstream_remote",
     (