[...]

  git checkout -b new_branch_name
HEAD is now at aac721b... - updated to 6.14.12 (note: new soname)
error: HEAD does not point to a branch
fatal: @{u} - not something we can merge
No conditional flags passed
from available:
--with   :	
--without:	 tests
Available branches: master
--2014-08-01 15:17:23--  http://distfiles.pld-linux.org/distfiles/by-md5/a/2/a2b13832e23ad9026bd249d57b6c26da/libpgf-src-6.14.12.tar.gz
Resolving distfiles.pld-linux.org (distfiles.pld-linux.org)... 193.239.45.41
Connecting to distfiles.pld-linux.org (distfiles.pld-linux.org)|193.239.45.41|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 91154 (89K) [application/x-gzip]
Saving to: 'libpgf-src-6.14.12.tar.gz'
     0K .......... .......... .......... .......... .......... 56%  765K 0s
    50K .......... .......... .......... .........            100%  609K=0.1s
2014-08-01 15:17:23 (688 KB/s) - 'libpgf-src-6.14.12.tar.gz' saved [91154/91154]
Building target platforms: i686-linux
Wrote: /home/users/builder/rpm/SRPMS/libpgf-6.14.12-1.src.rpm
exit status 0
Tagging with prefix: auto/ti/
Version: 6.14.12
Release: 1
tag: auto/ti/libpgf-6.14.12-1
Searching for tag auto/ti/libpgf-6.14.12-1...
Everything up-to-date
On detached HEAD. Use -r BRANCHNAME to override
error: Macro %_builddir has empty body
error: Macro %_builddir has empty body
Executing(--clean):  env -i TMP=/home/users/builder/tmp PATH=/bin:/usr/bin:/usr/sbin:/sbin:/usr/X11R6/bin HOME=/home/users/builder TMPDIR=/home/users/builder/tmp  /bin/sh -e /home/users/builder/tmp/rpm-tmp.52561
+ umask 022
+ cd /home/users/builder/rpm/BUILD
+ rm -rf libpgf
Begin-PLD-Builder-Info
Build-Time: user:2.26s sys:0.97s real:4.39s (faults io:0 non-io:144995)
Files queued for ftp:
     97609 libpgf-6.14.12-1.src.rpm
       186 libpgf-6.14.12-1.src.rpm.uploadinfo
End-PLD-Builder-Info