M= m*2l

when wire is bent into semi cicular arc pole strength remains unchanged but seperation between the poles changes.

if r is the radius of the semi circular arc

then,

2l= (pi)*r or  r= 2l/ (pi)

new seperation = 2r = 2*2l/(pi)

Magnetic moment(new)= m* 2*2l/(pi)= 2M/(pi)