Allow choosing field for author in named branch

This adds a setting for choosing which of {name, email, username} to use
as "author" when constructing the name for the branch to where a change
is downloaded.

The rationale is that sometimes the given "name" is just long and
unwieldy (when displaying the branch in the shell prompt, for example),
and one may be already used to the "username".

Change-Id: Ieed465f69ed0c0864979a92f609bd8f58cd8e883

git-review.1

@@ -292,6 +292,12 @@ This setting takes precedence over repository\-specific configuration
 in the
 .Pa .gitreview
 file.
+.It gitreview.branchauthor
+This setting changes the look of the author part when naming the local
+branch of a downloaded change.  Value must be one of "name", "email",
+or "username". Default is "name". See also the
+.Fl \-download
+option.
 .El
 .Bl -tag
 .It color.review

git_review/cmd.py

@@ -43,7 +43,7 @@ GLOBAL_CONFIG = "/etc/git-review/git-review.conf"
 USER_CONFIG = os.path.join(CONFIGDIR, "git-review.conf")
 DEFAULTS = dict(scheme='ssh', hostname=False, port=None, project=False,
                 branch='master', remote="gerrit", rebase="1",
-                track="0", usepushurl="0", notopic=False)
+                track="0", usepushurl="0", notopic=False, branchauthor="name")
 COPYRIGHT = """\
 Copyright (C) 2011-2020 OpenStack LLC.
 
@@ -69,6 +69,7 @@ _use_color = None
 _orig_head = None
 _rewrites = None
 _rewrites_push = None
+BRANCHAUTHOR = None
 
 
 class colors(object):
@@ -732,6 +733,7 @@ def load_config_file(config_file):
         'track': 'track',
         'notopic': 'notopic',
         'usepushurl': 'usepushurl',
+        'branchauthor': 'branchauthor',
     }
     config = {}
     for config_key, option_name in options.items():
@@ -1200,7 +1202,8 @@ def fetch_review(review, masterbranch, remote, project):
     except KeyError:
         topic = review
     try:
-        author = re.sub(r'\W+', '_', review_info['owner']['name']).lower()
+        author = re.sub(r'\W+', '_',
+                        review_info['owner'][BRANCHAUTHOR]).lower()
     except KeyError:
         author = 'unknown'
     remote_branch = review_info['branch']
@@ -1413,7 +1416,19 @@ git-review is a tool that helps submitting git branches to gerrit for
 review.
 """
 
-    parser = argparse.ArgumentParser(usage=usage, description=description)
+    epilog = """\
+additional information:
+
+  Options configurable using: git config --global gitreview.OPTION VALUE
+
+  branchauthor          name (default), username, email
+"""
+
+    parser = argparse.ArgumentParser(
+        usage=usage,
+        description=description,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        epilog=epilog)
 
     topic_arg_group = parser.add_mutually_exclusive_group()
     topic_arg_group.add_argument("-t", "--topic", dest="topic",
@@ -1607,6 +1622,13 @@ review.
     yes = options.yes
     status = 0
 
+    global BRANCHAUTHOR
+    BRANCHAUTHOR = config['branchauthor']
+    if BRANCHAUTHOR not in ["name", "email", "username"]:
+        warn("Invalid gitreview.branchauthor: %s (using default: %s)"
+             % (BRANCHAUTHOR, DEFAULTS["branchauthor"]))
+        BRANCHAUTHOR = DEFAULTS["branchauthor"]
+
     if options.track:
         remote, branch = resolve_tracking(remote, branch)