bug#15328: Bug or dubious feature?

[Linda Walsh]

Whatever the problem is, it's not in 'mv'...

I tried to run my dedup'r, and got this:
  /usr/share/fonts/sys> time ndedup /home/law/fonts/sys2/ .
  Paths: 34474, uniq nodes: 20192, total_size: 12.8GB (12.9GB allocated).
  ERROR: Invalid cross-device link doing link(./desktop.ini, 
/home/law/fonts/sys2//desktop.ini): \
    (Invalid cross-device link) at /home/law/bin/ndedup line 1107
  10.40sec 10.11usr 0.28sys (99.98% cpu)
----

But this works (same dir's):

  /usr/share/fonts/sys> cd /home/share/fonts/sys
  /home/share/fonts/sys> time ndedup /home/law/fonts/sys2/ .
  Paths: 34474, uniq nodes: 20191, total_size: 12.8GB (12.9GB allocated).
   Nodes(done/uniq); Space(read / alloc'd)
    35011/12758    25.5GB / 7.2GB space  ;cursz:  37.8MB; newlnks: 7433(1730 
cmps_skip, 11046 cmps_full)
  5.7GB in 7434 duplicate files found found.
  49.75sec 35.34usr 12.90sys (96.98% cpu)

Anyone know if this is a documented kernel "feature"?
Seems odd.