http://image.noelshack.com/fichiers/2016/01/1452116009-rotation-bloc.png
The rotated texture's problem was already reported around 8 months~1 year ago but with the migration to phab the discussions seems gone or not accessible anymore.
In a nutshell the problem was cause by placing unrotatable block (i. e. power generator/capacitor, hull, armor, etc.) and rotate it by CTRL+mouse wheel. It seems you try solved this by refrain rotation to apply with combinaison when the player use "unrotatable block" (note : Howewer the arrow still continue to turn during a micro-fraction of second. I didn't try yet to put block at the same time, but it's out of topic)
Anyway, you applied an ineffective restriction because, indeed, you prevent players to be able to rotate block but you don't prevent the software to apply this rotation. So I accidentally bypass the restriction (cf. "step to reproduce").
Let's see this :
Below, how the advanced grey hull blocks are when rotate in default/good way (front face = left side). Look the uniform color of the top edge of the front blocks line.
http://image.noelshack.com/fichiers/2016/01/1452115006-otation-bloc-armure-avancee-correcte-ok.png
Compare the same edge there. The 3 left blocks have front face below while the rest of block lines face the left. You can clearly see the demarcation between the 3rd & 4th block (starting left). Note also my yellow build mode cursor actually turning below, position it shouldn't suppose be able to reach when I manipulate armor.
http://image.noelshack.com/fichiers/2016/01/1452116001-rotation-bloc-armure-avancee-illustree.png
Here the left build block is in good default side (frontface backward, toward the planet), the right build block face below. Note my yellow cursor face below due to the gravity block...
http://image.noelshack.com/fichiers/2016/01/1452116006-apres-gravite.png
...and then I switched to build block and place to the left of the good one. See the result.
http://image.noelshack.com/fichiers/2016/01/1452115992-apres-gravite-2.png
It's not proper to the gravity block, I can do that with all rotable block, like wedge. Actually I'm not complaining too much of that because i can put the walking man of the gravity block in all side ← ↑ → ↓ . It's just come really tricky with armor things.