VMware: fix regression for 'TaskInProgress'

Commit 73d4a7c1b4681accd993c1109a9eff837ff612f4 caused a regression
with the snapshot deletion. That is, the snapshot deletion will retry
if the resource is busy. The fact that the exception was not supported
in olso caused the problem.

Version 0.6.0 supports this exception.

Change-Id: I12fcc7d039a123e681c51978b9cf632af8f9644b
Closes-bug: #1369463
Merge "VMware: fix regression for 'TaskInProgress'"