see #4656 comment 3 for a description of the problem: when the cc is captured, units which were on alert can be ungarrisoned by the enemy
the patch contains also a few other fixes (reset the productionQueue is really owned before resetting it and allow a same productionQueue to be on alert by 2 cc)
As said in #4656 the way to deal with units under alert when the cc is captured or destroyed cannot be easily fixed in the current design, so the design of the component will certainly have to be changed once A22 is released