crash in darwin CFDictionaryGetValue

This has happened a couple of times on my system. Not sure what the context is.

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 com.apple.CoreFoundation 0x00007fff9167a877 CFDictionaryGetValue + 23
1 _ctypes.so 0x00000001031d909c ffi_call_unix64 + 76
2 _ctypes.so 0x00000001031d984b ffi_call + 755
3 _ctypes.so 0x00000001031d4e73 _ctypes_callproc + 767
4 _ctypes.so 0x00000001031cefc5 0x1031cc000 + 12229
5 org.python.python 0x000000010068d14d PyObject_Call + 97
6 org.python.python 0x0000000100707bc6 PyEval_EvalFrameEx + 7585
7 org.python.python 0x000000010070c5c0 0x100683000 + 562624
8 org.python.python 0x0000000100707a73 PyEval_EvalFrameEx + 7246
9 org.python.python 0x000000010070c5c0 0x100683000 + 562624
10 org.python.python 0x0000000100707a73 PyEval_EvalFrameEx + 7246
11 org.python.python 0x000000010070c5c0 0x100683000 + 562624
12 org.python.python 0x0000000100707a73 PyEval_EvalFrameEx + 7246
13 org.python.python 0x0000000100705de1 PyEval_EvalCodeEx + 1920
14 org.python.python 0x000000010070c636 0x100683000 + 562742
15 org.python.python 0x0000000100707a73 PyEval_EvalFrameEx + 7246
16 org.python.python 0x0000000100705de1 PyEval_EvalCodeEx + 1920
17 org.python.python 0x00000001007085a3 PyEval_EvalFrameEx + 10110
18 org.python.python 0x0000000100705de1 PyEval_EvalCodeEx + 1920
19 org.python.python 0x000000010070c636 0x100683000 + 562742
20 org.python.python 0x0000000100707a73 PyEval_EvalFrameEx + 7246
21 org.python.python 0x0000000100705de1 PyEval_EvalCodeEx + 1920
22 org.python.python 0x000000010070565b PyEval_EvalCode + 54
23 org.python.python 0x00000001007249fe 0x100683000 + 662014
24 org.python.python 0x0000000100724aca PyRun_FileExFlags + 165
25 org.python.python 0x00000001007244b4 PyRun_SimpleFileExFlags + 410
26 com.ubuntu.one.controlpanel 0x000000010000437f 0x100000000 + 17279
27 com.ubuntu.one.controlpanel 0x0000000100004aee main + 1438
28 com.ubuntu.one.controlpanel 0x0000000100000cb4 start + 52