Skullstripping is done by AFNI.
Input of Skullstripping *.anat.nii ..
3dinfo -av_space +orig
nifti_tool:
intent_code 68 1 0
slice_code 122 1 0
qform_code 252 1 1
sform_code 254 1 1
and same output after skullstripping. So my guess was wrong that skullstripping is changing the space.
After this, I am using nifti_tool -rm_ext ALL -prefix *.anat.corr.nii -infiles *.anat.nii
and these *.corr.nii files give different output for the same commands.
3dinfo -av_space +tlrc
nifti_tool
intent_code 68 1 0
slice_code 122 1 0
qform_code 252 1 1
sform_code 254 1 2