tools/upip.py: Skip '.frozen' entry in sys.path for install path.

Signed-off-by: Damien George <damien@micropython.org>

tools/upip.py

@@ -262,6 +262,8 @@ def get_install_path():
     if install_path is None:
         # sys.path[0] is current module's path
         install_path = sys.path[1]
+        if install_path == ".frozen":
+            install_path = sys.path[2]
     install_path = expandhome(install_path)
     return install_path
 
@@ -281,11 +283,11 @@ upip - Simple PyPI package manager for MicroPython
 Usage: micropython -m upip install [-p <path>] <package>... | -r <requirements.txt>
 import upip; upip.install(package_or_list, [<path>])
 
-If <path> is not given, packages will be installed into sys.path[1]
-(can be set from MICROPYPATH environment variable, if current system
-supports that)."""
+If <path> isn't given, packages will be installed to sys.path[1], or
+sys.path[2] if the former is .frozen (path can be set from MICROPYPATH
+environment variable if supported)."""
     )
-    print("Current value of sys.path[1]:", sys.path[1])
+    print("Default install path:", get_install_path())
     print(
         """\