9d7a9b83ed
tripleo-container-image-prepare can consume a lot of memory during the export. Previously, when a MemoryError was raised by python, the exception was hidden because there was no message in the exception and the code re-raised an IOError. This patch updates the code so that a MemoryError is specifically caught if one was thrown, and an accurate message is logged. Change-Id: I6de47600f430d3af5e3052ff456cd718a0df0d76