As already noted, the form wrapper currently only works for float ed elements, so this exact situation does not work with CSS just because only a wrapper on one side of the form is allowed (expected). After CSS Shapes 2 and / or Exclusions from the CSS specification), we can do this not only with forms, but also with image transparency.
I ran into the same problem trying to figure out how CSS forms and columns interact (spoiler: decent, but not organic). The problem is that the layout algorithm looks for the farthest edge (ignoring the possibility of multiple sides), and then starts the layout of the content from this coordinate. For items in the middle, this means that you only get text on one side. For CSS columns (as I understand it), the layout starts again from the farthest edge, but then continues right down, and does not wrap itself in the form on each line (see fiddle ), so protrusions in the shapes (for example, the polygon star) can actually make the wrapping content will be below the whole figure, and not flatten to the side or flow down into the ledge.
(note that in the 2nd example there are 3 sets of 2 columns)
However, there are several options that may work for such situations. I adapted the following from other answers / comments, but had to make a few changes to make them work (and some of the CSS attributes were experimental and no longer valid), so I felt this was better than the new answer than how it edits / comments:
Wrap one side
Use shape-outside in the left float ed div to create a wrapper circle, then use margin-left to push it off the left side. I added a circle inside the div to illustrate (your image URL is 404), but he had to adjust the location because Chrome did not calculate its position as you would expect once the fields were added.
http://jsfiddle.net/brichins/50h20kxa/1/

Columns and Mirror Wrap Elements
If the columns are acceptable, manually (see the discussion of CSS columns) creating 2 containers for the columns and placing the shape d element on each side gives the following:
http://jsfiddle.net/brichins/gvhpfccu/

The disadvantage here is the columns where you may need one block (not necessarily bad for readability), as well as to calculate the appropriate separation for your content.
Reading