While setting up a build environment for Borg from Guix commit
9e783d0bf22a7ff965105eb45f6c179a832bbabf, I noticed a profile collision
between python-six and python-six-bootstrap, with the bootstrap package
winning the contest:

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building /gnu/store/lz09hrr9z0p9xc44n31sjvpykfwq38f1-manual-database.drv...
Creating manual page database...
353 entries processed in 2.7 s
successfully built /gnu/store/lz09hrr9z0p9xc44n31sjvpykfwq38f1-manual-database.drv
building /gnu/store/bs1961881nfibryf60wrcxsn2dcjhg5k-profile.drv...

warning: collision encountered:
  /gnu/store/zjn8f7rmfjhc6l2xczplbk1b9kmj38wx-python-six-bootstrap-1.11.0/lib/python3.6/site-packages/__pycache__/six.cpython-36.pyc
  /gnu/store/mglmyk8xd86d8mdgmk54vs6vzksr3j6n-python-six-1.11.0/lib/python3.6/site-packages/__pycache__/six.cpython-36.pyc
warning: choosing /gnu/store/zjn8f7rmfjhc6l2xczplbk1b9kmj38wx-python-six-bootstrap-1.11.0/lib/python3.6/site-packages/__pycache__/six.cpython-36.pyc

warning: collision encountered:
  /gnu/store/b5x786d3h552j2zp4ppvlz9dkbiqy2ng-ld-wrapper-0/bin/ld
  /gnu/store/srmqh29dpm50j8kj1pbqg2rgh053wgyp-binutils-2.30/bin/ld
warning: choosing /gnu/store/b5x786d3h552j2zp4ppvlz9dkbiqy2ng-ld-wrapper-0/bin/ld
successfully built /gnu/store/bs1961881nfibryf60wrcxsn2dcjhg5k-profile.drv
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These package "bootstrap" packages shouldn't be referenced in profiles,
right?