Up to today I had the same problem. I tried the quick solution to trashing the preferences first (hitting cmd+alt+ctrl+shift immediately after starting Photoshop and confirming the dialog) and I still had 2 additional pixels on each side when using the # vector layer. 

After that I manually deleted/renamed the Photoshop preference file. (https://forums.adobe.com/thread/963474?tstart=0)
And whatever the difference between these two methods may be, when I fired up Photoshop again, everything worked just fine. Exporting a single pixel using a vector shape - no problem!

I’m running Photoshop CS6 on OSX 10.8.5. Hope that helps ...

Sonu, there might be an easy solution/workaround for your request (at least on Apple machines). Whenever I accidentally hit the „export all assets“ instead of the „export selected layer“ (aarggh!) I repeatedly hit [CMD] + [ . ] –  This produces an error in C&S but at least it stops the process …