[...]

do so (now or later) by using -b with the checkout command again. Example:
  git checkout -b new_branch_name
HEAD is now at 874b674... - updated to 1.22, separated -apidocs
fatal: HEAD does not point to a branch
Available branches: master
Searching for tag auto/ti/pkcs11-helper-1.22-1...
Searching for tag auto/ti/pkcs11-helper-1_22-1...
--2018-03-07 11:05:08--  http://distfiles.pld-linux.org/distfiles/by-md5/c/7/c7824ef1faa357a185ae1660fb669da3/pkcs11-helper-1.22.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: 417494 (408K) [application/x-bzip2]
Saving to: 'pkcs11-helper-1.22.tar.bz2'
     0K .......... .......... .......... .......... .......... 12% 1.23M 0s
    50K .......... .......... .......... .......... .......... 24% 2.44M 0s
   100K .......... .......... .......... .......... .......... 36%  175M 0s
   150K .......... .......... .......... .......... .......... 49% 56.9M 0s
   200K .......... .......... .......... .......... .......... 61% 2.55M 0s
   250K .......... .......... .......... .......... .......... 73% 80.7M 0s
   300K .......... .......... .......... .......... .......... 85% 90.8M 0s
   350K .......... .......... .......... .......... .......... 98% 66.0M 0s
   400K .......                                               100% 22.9M=0.08s
2018-03-07 11:05:08 (4.84 MB/s) - 'pkcs11-helper-1.22.tar.bz2' saved [417494/417494]
Building target platforms: i686-linux
Wrote: /home/users/builder/rpm/SRPMS/pkcs11-helper-1.22-1.src.rpm
exit status 0
Tagging with prefix: auto/ti/
HEAD is now at 874b674... - updated to 1.22, separated -apidocs
fatal: HEAD does not point to a branch
Writing git revision for tag auto/ti/pkcs11-helper-1.22-1
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.69018
+ umask 022
+ cd /home/users/builder/rpm/BUILD
+ rm -rf pkcs11-helper-1.22
Begin-TLD-Builder-Info
Build-Time: user:0.78s sys:0.14s real:3.09s (faults io:1 non-io:93354)
Files queued for ftp:
    422956 pkcs11-helper-1.22-1.src.rpm
       190 pkcs11-helper-1.22-1.src.rpm.uploadinfo
End-TLD-Builder-Info