Ubuntu Gnome 14.04 x64, AMD A8-3870K (APU)
Broken: 2.72 eb464ee
Short description of error
Passing a specific vertex group of adjacent edges to be bevelled doesn't work as intended and rather bevels all the edges connected to them or those between two or more marked edges. Tried on several primitives, it also seems to only happen when the edges are adjacent or not directly connected to each other.
Exact steps for others to reproduce the error
Add a cube, select two adjacent edges and add them to a vertex group. Next add a bevel modifier, select vertex group as the limit method using the vertex group you created and attempt to change width or segments to see the bevel. Both the edges connected to the adjacent ones are bevelled as well.