macOS: Ensure that when running from a bundle, the bundle kitty exe is preferred over any kitty in PATH

Fix #1280

docs/changelog.rst

@@ -15,6 +15,8 @@ Changelog
 - macOS: Fix dragging kitty window tabs in traditional full screen mode causing
   crashes (:iss:`1296`)
 
+- macOS: Ensure that when running from a bundle, the bundle kitty exe is
+  preferred over any kitty in PATH (:iss:`1280`)
 
 0.13.2 [2019-01-04]
 ------------------------------

kitty/main.py

@@ -231,7 +231,7 @@ def _main():
     rpath = os.path.dirname(kitty_exe())
     items = frozenset(os.environ['PATH'].split(os.pathsep))
     if rpath and rpath not in items:
-        os.environ['PATH'] += os.pathsep + rpath
+        os.environ['PATH'] = rpath + os.pathsep + os.environ.get('PATH', '')
 
     args = sys.argv[1:]
     if is_macos and os.environ.pop('KITTY_LAUNCHED_BY_LAUNCH_SERVICES', None) == '1':