Merge pull request ARMmbed#10406 from j3hill/cmsis_fix

Modify CMSIS pack manager to properly handle OSError

Author: 0xc0170

tools/arm_pack_manager/__init__.py

@@ -23,7 +23,7 @@
 try:
     from cmsis_pack_manager import Cache as _Cache
     _CPM_PRESENT = True
-except ImportError:
+except (ImportError, OSError):
     _CPM_PRESENT = False
 
 from tools.flash_algo import PackFlashAlgo