cubicweb-vcsfile #5102904 truncate author field [validation pending]

When importing changesets, the author field may be large (more than 200 chars).

There is a constraint that limits the author field up to 200 chars. This is a soft constraint. The author field shall be cut up to 200 chars (cubicweb.utils.cut ?) instead of raising a validation error.

done in2.1.0
load left0.000
closed by#cc8cebdcdf2d [hg] truncate if it's too long (closes #5102904)
patch[hg] truncate if it's too long (closes #5102904) [applied]