Relates to: T20262

Description:
The "mark seam" command from the search box (space bar) marks or clears an edge depending on what the last command did. So for example, if the command "clear seam" from the mesh menu is executed, then pressing space bar and entering "mark seam" doesn't mark a seam as would be expected.

Version: 2.62

Steps to reproduce:
1 - start blender
2 - enter edit mode (make sure the cube is selected)
3 - select an edge
4 - press space bar and enter and execute "mark seam". Notice how the edge is marked as expected
5 - notice that there's no way to clear the seam using the search box (space bar)
6 - clear the seam using the mesh menu (Mesh -> Edges -> Clear Seam)
7 - Now try to mark an edge using the search box (space bar). It's not possible. "mark seam" will always clear a seam.