this derivation will be built:
  /nix/store/kmffyc5wsyp6dybayim7pwzsbxb6cf5y-spec-xmllint.drv
building '/nix/store/kmffyc5wsyp6dybayim7pwzsbxb6cf5y-spec-xmllint.drv'
spec-xmllint> invalid/a.xml:2: parser error : Premature end of data in tag b line 1
spec-xmllint> 
spec-xmllint> ^
spec-xmllint> invalid/a.xml:2: parser error : Premature end of data in tag b line 1
spec-xmllint> 
spec-xmllint> ^

upload niks3: ok