ports/182651: multimedia/ffmpeg - install fails with many "Could not unlink" messages

[parv]

>Number:         182651
>Category:       ports
>Synopsis:       multimedia/ffmpeg - install fails with many "Could not unlink" messages
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-ports-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Oct 04 22:50:00 UTC 2013
>Closed-Date:
>Last-Modified:
>Originator:     parv
>Release:        8-STABLE
>Organization:
>Environment:
FreeBSD holstein.holy.cow 8.4-PRERELEASE FreeBSD 8.4-PRERELEASE #1 r249093: Thu Apr  4 03:49:16 HST 2013     root at holstein.holy.cow:/misc/obj/misc/src.svn/8/sys/X200-SMP.8  i386
>Description:
In ports tree updated as of r329392, installation of multimedia/ffmpeg fails ...

===>  Installing for ffmpeg-0.7.15_1,1
===>  Checking if multimedia/ffmpeg already installed
share/doc/ffmpeg/APIchanges: Could not unlink
share/doc/ffmpeg/RELEASE_NOTES: Could not unlink
share/doc/ffmpeg/TODO: Could not unlink
share/doc/ffmpeg/avutil.txt: Could not unlink
share/doc/ffmpeg/build_system.txt: Could not unlink
share/doc/ffmpeg/developer.html: Could not unlink
share/doc/ffmpeg/faq.html: Could not unlink
share/doc/ffmpeg/fate.txt: Could not unlink
share/doc/ffmpeg/ffmpeg.html: Could not unlink
share/doc/ffmpeg/ffplay.html: Could not unlink
share/doc/ffmpeg/ffprobe.html: Could not unlink
share/doc/ffmpeg/ffserver.html: Could not unlink
share/doc/ffmpeg/general.html: Could not unlink
share/doc/ffmpeg/git-howto.txt: Could not unlink
share/doc/ffmpeg/issue_tracker.txt: Could not unlink
share/doc/ffmpeg/libavfilter.html: Could not unlink
share/doc/ffmpeg/multithreading.txt: Could not unlink
share/doc/ffmpeg/optimization.txt: Could not unlink
share/doc/ffmpeg/rate_distortion.txt: Could not unlink
share/doc/ffmpeg/snow.txt: Could not unlink
share/doc/ffmpeg/soc.txt: Could not unlink
share/doc/ffmpeg/swscale.txt: Could not unlink
share/doc/ffmpeg/tablegen.txt: Could not unlink
share/doc/ffmpeg/viterbi.txt: Could not unlink
tar: Error exit delayed from previous errors.
pkg_add: leave_playpen: can't chdir back to ''
*** Error code 2


Stop in /misc/ports/multimedia/ffmpeg.
>How-To-Repeat:
Above problem is 100% reproducible on my machine via ...

  cd /misc/ports/multimedia/ffmpeg && make clean  && make install
>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: