Comment 2 for bug 992273

I found the problem with this bug. Turns out that scripts/orc/upgrade.lua had 3 lines in it with the word stronghold misspelt, instead reading "stronghol". So I changed it to Stronghold, all 3 lines that had this misspelt word, and the axethrower-to-berserker upgrade works perfectly now.

I'll add this as a patch so you guys can add it to the trunk.