Why does installing texlive download that 2 GB file twice?

[Konrad Hinsen]

Hi Guix,

I am building an environment containing texlive. I was prepared for a
huge download, but not for it to happen twice! Here's the log
(with some comments):

  The following derivations will be built:
     /gnu/store/mp6v3nngryf58l74l1j4y32dv60rp6qn-profile.drv
     /gnu/store/5bv2w5k8lgjwpzgyh31cyp8vxfg0rrnr-texlive-texmf-20180414.drv

OK.
  2,640.0 MB will be downloaded:
     /gnu/store/w02vdgqimzrby3yab4062yq34hjxz6nr-libyaml-0.1.7
     /gnu/store/byhjm99aabwh91csyjsaja83m7xlbln6-python-pyyaml-3.13
     /gnu/store/5aq60gx42sfs5drigb5g7fpa7fh1pq4z-texlive-20180414
     /gnu/store/jl8jj8d1s2ldvazylyfgmz7ga7rvcgxx-module-import-compiled
     /gnu/store/mj40l554qxw15acz0h018gk5c9mxzfgn-texlive-20180414-texmf.tar.xz
     /gnu/store/w3jlc8pk8416m7h677r5vq92b66h8cqd-module-import
     /gnu/store/dch016c5w3zijqrpkhsky89s81jk7p41-cairo-1.16.0
     /gnu/store/18q4r8bpwmpm4w15zipf66l3bvdjzfbs-poppler-0.79.0
     /gnu/store/xypzclmh2i1nkzyyb1crmhpbngx3pcmw-ruby-2.5.3
     /gnu/store/15zh79zna12m45afl6h1rclsnfsw7m7b-ghostscript-9.27
     /gnu/store/94nw4ch1gjn6pqdb54a90k6cvnx3lag3-potrace-1.15
     /gnu/store/l06xm6ax5j99gkqjkbwsrb0353l2fclz-zziplib-0.13.69
     /gnu/store/543ybxjpmkpwzcbdxmlr3x8qwpxlb1hw-teckit-2.5.9
     /gnu/store/azd3rg350gjkgzvzps3s4j3kpz5kxh57-texlive-bin-20180414
     /gnu/store/78w7y0lxar70j512iqw8x3nimzj10yga-python-3.7.4
     /gnu/store/6r0hkmky937g824g02c8mzyhq80vjql4-python-3.7.4-tk

Make sense. That's 2.6 GB.

  The following grafts will be made:
     /gnu/store/j3xfkw271db0bnvkylf8fik3dqnmwwck-python-3.7.4.drv
     /gnu/store/vcbpxwrrkk1frp1kgdbn86dm87l1zl85-texlive-20180414.drv
     /gnu/store/97c19j1dnxsjshmpp80p6hfi4v4bg0by-texlive-bin-20180414.drv
     /gnu/store/bs7w34zc6a0sznbln8wmsbrdjdhfzpmk-teckit-2.5.9.drv
     /gnu/store/cb0aag3qha7znkrv9z12j2smvk3kn8h2-ruby-2.5.3.drv
     /gnu/store/dqn2lf7755s4wl4kn49m4b18va5yvxjz-texlive-texmf-20180414.drv
     /gnu/store/w7ynpv1wyvcqk8lkzwkgblik5gl5q0r2-python-pyyaml-3.13.drv
  The following profile hooks will be built:
     /gnu/store/609kij4ac4154x3aslmpwpiq8b6kpb5g-fonts-dir.drv
     /gnu/store/6ckxy3rmh55dd95zr94wx3q063q1bhv1-info-dir.drv
     /gnu/store/v7wnqdpbfk9yd1kfdsa013rj22jy47id-manual-database.drv
     /gnu/store/yqzsdl5b4mmfplbhp08lskb5m0g2v1iq-ca-certificate-bundle.drv

Looks OK as well. And now...

  downloading from 
https://ci.guix.gnu.org/nar/mj40l554qxw15acz0h018gk5c9mxzfgn-texlive-20180414-texmf.tar.xz...
   texlive-20180414-texmf.tar.xz  2.42GiB 1.4MiB/s 29:22 [##################] 
100.0%

That's my 2 GB of TeXLive. Some small stuff follows:

  downloading from 
https://ci.guix.gnu.org/nar/lzip/dch016c5w3zijqrpkhsky89s81jk7p41-cairo-1.16.0...
   cairo-1.16.0  1.0MiB                 3.0MiB/s 00:00 [##################] 
100.0%

  downloading from 
https://ci.guix.gnu.org/nar/lzip/15zh79zna12m45afl6h1rclsnfsw7m7b-ghostscript-9.27...
   ghostscript-9.27  10.9MiB            4.8MiB/s 00:02 [##################] 
100.0%

  downloading from 
https://ci.guix.gnu.org/nar/lzip/w02vdgqimzrby3yab4062yq34hjxz6nr-libyaml-0.1.7...
   libyaml-0.1.7  70KiB                 1.6MiB/s 00:00 [##################] 
100.0%

  downloading from 
https://ci.guix.gnu.org/nar/gzip/w3jlc8pk8416m7h677r5vq92b66h8cqd-module-import...
   module-import  334B                   29KiB/s 00:00 [##################] 
100.0%

  downloading from 
https://ci.guix.gnu.org/nar/lzip/18q4r8bpwmpm4w15zipf66l3bvdjzfbs-poppler-0.79.0...
   poppler-0.79.0  1.3MiB               4.4MiB/s 00:00 [##################] 
100.0%

  downloading from 
https://ci.guix.gnu.org/nar/lzip/jl8jj8d1s2ldvazylyfgmz7ga7rvcgxx-module-import-compiled...
   module-import-compiled  166KiB       2.0MiB/s 00:00 [##################] 
100.0%

  downloading from 
https://ci.guix.gnu.org/nar/lzip/94nw4ch1gjn6pqdb54a90k6cvnx3lag3-potrace-1.15...
   potrace-1.15  96KiB                  1.9MiB/s 00:00 [##################] 
100.0%

  downloading from 
https://ci.guix.gnu.org/nar/lzip/6r0hkmky937g824g02c8mzyhq80vjql4-python-3.7.4-tk...
   python-3.7.4-tk  29KiB               2.2MiB/s 00:00 [##################] 
100.0%

  downloading from 
https://ci.guix.gnu.org/nar/lzip/byhjm99aabwh91csyjsaja83m7xlbln6-python-pyyaml-3.13...
   python-pyyaml-3.13  148KiB           1.7MiB/s 00:00 [##################] 
100.0%

  downloading from 
https://ci.guix.gnu.org/nar/lzip/xypzclmh2i1nkzyyb1crmhpbngx3pcmw-ruby-2.5.3...
   ruby-2.5.3  5.5MiB                   1.7MiB/s 00:03 [##################] 
100.0%

  downloading from 
https://ci.guix.gnu.org/nar/lzip/543ybxjpmkpwzcbdxmlr3x8qwpxlb1hw-teckit-2.5.9...
   teckit-2.5.9  445KiB                 2.3MiB/s 00:00 [##################] 
100.0%

  downloading from 
https://ci.guix.gnu.org/nar/lzip/l06xm6ax5j99gkqjkbwsrb0353l2fclz-zziplib-0.13.69...
   zziplib-0.13.69  93KiB               1.3MiB/s 00:00 [##################] 
100.0%

  downloading from 
https://ci.guix.gnu.org/nar/lzip/azd3rg350gjkgzvzps3s4j3kpz5kxh57-texlive-bin-20180414...
   texlive-bin-20180414  12.6MiB        5.2MiB/s 00:02 [##################] 
100.0%

But then:

  downloading from 
https://ci.guix.gnu.org/nar/lzip/zkcd3i5r98rh36cp9is1l5griiyrgvap-texlive-texmf-20180414...
   texlive-texmf-20180414  2.38GiB      1.4MiB/s 25:41 [################  ]  
89.2%

That looks like the same data downloaded again. Why that?

Cheers,
  Konrad.