269
« on: January 26, 2016, 12:06:42 pm »
Near as I can tell -- but this is still just speculation -- dwarves seem to pre-select where they are going to stand when they do a job, before they actually get to the job site. Now, it's not as bad in the current versions as it used to be. Dwarves who have to pick up a building material object along the way tend to stand on the side of the site that the object came from, so they don't wall themselves in quite as often as they used to do.
Nevertheless, dwarves are persistently stupid and inflexible about construction. At some point, the spot they will stand for a given job is decided, and that decision is final. That is where they will stand. If you suspend the job and resume it later, they'll come back to that same spot.
Now, "creature occupying site" can mean an animal, or a dwarf, and that includes the dwarf doing the construction. There used to be a horrible epidemic of dwarves standing on the spot where they are building a wall, and suspending the job because there's a dwarf in the way. There was a bug fix for this, and now it happens a lot less often, but it's still something that occasionally happens.
Since dwarves do not have the imagination required to stand in a different spot after you resume a suspended job, they keep going right onto the construction site, and then -- surprise! -- there's a dwarf in the construction site, so they can't build there. The only fix is to completely cancel that job and try it again.
On the other hand, if it's an animal that's in the way, you might be able to get the job finished simply by retrying, when the animals are no longer there. It helps if your crazy cat lady dwarves are not on the construction site.