[...]

do so (now or later) by using -b with the checkout command again. Example:
  git checkout -b new_branch_name
HEAD is now at bf2bf49... - updated to 1.2.9 - removed obsolete mibstore,xserver-1.19 patches
fatal: HEAD does not point to a branch
Available branches: master
Searching for tag auto/ti/xorg-driver-video-glint-1.2.9-1...
Searching for tag auto/ti/xorg-driver-video-glint-1_2_9-1...
--2018-03-15 09:16:55--  http://distfiles.pld-linux.org/distfiles/by-md5/3/d/3d166b7a97d96007272ffc153d5f81fd/xf86-video-glint-1.2.9.tar.bz2
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: 419524 (410K) [application/x-bzip2]
Saving to: 'xf86-video-glint-1.2.9.tar.bz2'
     0K .......... .......... .......... .......... .......... 12% 1.21M 0s
    50K .......... .......... .......... .......... .......... 24% 2.42M 0s
   100K .......... .......... .......... .......... .......... 36%  308M 0s
   150K .......... .......... .......... .......... .......... 48%  102M 0s
   200K .......... .......... .......... .......... .......... 61% 2.49M 0s
   250K .......... .......... .......... .......... .......... 73% 99.7M 0s
   300K .......... .......... .......... .......... .......... 85% 70.9M 0s
   350K .......... .......... .......... .......... .......... 97%  106M 0s
   400K .........                                             100%  352M=0.08s
2018-03-15 09:16:55 (4.86 MB/s) - 'xf86-video-glint-1.2.9.tar.bz2' saved [419524/419524]
Building target platforms: i686-linux
Wrote: /home/users/builder/rpm/SRPMS/xorg-driver-video-glint-1.2.9-1.src.rpm
exit status 0
Tagging with prefix: auto/ti/
HEAD is now at bf2bf49... - updated to 1.2.9 - removed obsolete mibstore,xserver-1.19 patches
fatal: HEAD does not point to a branch
Writing git revision for tag auto/ti/xorg-driver-video-glint-1.2.9-1
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 HOME=/home/users/builder PATH=/bin:/usr/bin:/usr/sbin:/sbin:/usr/X11R6/bin TMPDIR=/home/users/builder/tmp  /bin/sh -e /home/users/builder/tmp/rpm-tmp.29616
+ umask 022
+ cd /home/users/builder/rpm/BUILD
+ rm -rf xf86-video-glint-1.2.9
Begin-TLD-Builder-Info
Build-Time: user:0.54s sys:0.09s real:1.91s (faults io:0 non-io:91118)
Files queued for ftp:
    425319 xorg-driver-video-glint-1.2.9-1.src.rpm
       201 xorg-driver-video-glint-1.2.9-1.src.rpm.uploadinfo
End-TLD-Builder-Info