style: kill ersatz if-else ternary operators Although Python supports `X = Y if COND else Z`, this was only introduced in Python 2.5. Since we have to support Python 2.4, it was a very common thing to write instead `X = COND and Y or Z`, which is a bit obscure at a glance. It requires some intricate knowledge of Python to understand how to parse these one-liners. We change instead all of these one-liners to 4-liners. This was executed with the following perlism: find -name "*.py" -exec perl -pi -e 's,(\s*)([\.\w]+) = \(?(\S+)\s+and\s+(\S*)\)?\s+or\s+(\S*)$,$1if $3:\n$1 $2 = $4\n$1else:\n$1 $2 = $5,' {} \; I tweaked the following cases from the automatic Perl output: prev = (parents and parents[0]) or nullid port = (use_ssl and 443 or 80) cwd = (pats and repo.getcwd()) or '' rename = fctx and webutil.renamelink(fctx) or [] ctx = fctx and fctx or ctx self.base = (mapfile and os.path.dirname(mapfile)) or '' I also added some newlines wherever they seemd appropriate for readability There are probably a few ersatz ternary operators still in the code somewhere, lurking away from the power of a simple regex.

--- a/mercurial/context.py	Fri Mar 13 14:20:13 2015 -0400
+++ b/mercurial/context.py	Fri Mar 13 17:00:06 2015 -0400
@@ -963,7 +963,11 @@
     def ancestors(self, followfirst=False):
         visit = {}
         c = self
-        cut = followfirst and 1 or None
+        if followfirst:
+            cut = 1
+        else:
+            cut = None
+
         while True:
             for parent in c.parents()[:cut]:
                 visit[(parent.linkrev(), parent.filenode())] = parent
@@ -1755,7 +1759,11 @@
             # "filectxfn" for performance (e.g. converting from another VCS)
             self._filectxfn = util.cachefunc(filectxfn)
 
-        self._extra = extra and extra.copy() or {}
+        if extra:
+            self._extra = extra.copy()
+        else:
+            self._extra = {}
+
         if self._extra.get('branch', '') == '':
             self._extra['branch'] = 'default'