hg: don't attempt to extend `sys.path` with the user site without `APPDATA`

This variable is created by the system and *should* be available, but
test-lfs-bundle.t has a test where it is explicitly unset.  It wasn't caught
before because prior to 95af358fcdfe, it was limited to the py2exe binary.  As a
precaution, fix both that and the pyoxidizer case that was causing the test to
fail.

Differential Revision: https://phab.mercurial-scm.org/D11354

hg

@@ -28,9 +28,11 b" if libdir != '@' 'LIBDIR' '@':"
 # to the documentation.
 if getattr(sys, 'frozen', None) == 'console_exe':
     vi = sys.version_info
+    appdata = os.environ.get('APPDATA')
+    if appdata:
     sys.path.append(
         os.path.join(
-            os.environ['APPDATA'],
+                appdata,
             'Python',
             'Python%d%d' % (vi[0], vi[1]),
             'site-packages',

rust/hgcli/pyoxidizer.bzl

@@ -47,9 +47,11 b' if extra_path is not None:'
 # Add user site to sys.path to load extensions without the full path
 if os.name == 'nt':
     vi = sys.version_info
+    appdata = os.environ.get('APPDATA')
+    if appdata:
     sys.path.append(
         os.path.join(
-            os.environ['APPDATA'],
+                appdata,
             'Python',
             'Python%d%d' % (vi[0], vi[1]),
             'site-packages',