mip: Make mip.install() skip /rom*/lib directories.

If a ROMFS is mounted then "/rom/lib" is usually in `sys.path` before the
writable filesystem's "lib" entry.  The ROMFS directory cannot be installed
to, so skip it if found.

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

micropython/mip/manifest.py

@@ -1,4 +1,4 @@
-metadata(version="0.4.0", description="On-device package installer for network-capable boards")
+metadata(version="0.4.1", description="On-device package installer for network-capable boards")
 
 require("requests")
 

micropython/mip/mip/__init__.py

@@ -171,7 +171,7 @@ def _install_package(package, index, target, version, mpy):
 def install(package, index=None, target=None, version=None, mpy=True):
     if not target:
         for p in sys.path:
-            if p.endswith("/lib"):
+            if not p.startswith("/rom") and p.endswith("/lib"):
                 target = p
                 break
         else: