Why is this OR dependency not working as I expected

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http://unix.stackexchange.com – I tried to remove python2.6 from my Debian system: $ sudo apt-get purge python2.6 Reading package lists... Done Building dependency tree Reading state information... Done The following packages will be REMOVED: fabric* python-nose* python-pip* python2.6* 0 upgraded, 0 newly installed, 4 to remove and 0 not upgraded. After this operation, 11.0 MB disk space will be freed. Do you want to continue [Y/n]? n Abort. I did not expect to have fabric to be removed because it has an OR dependency on python2.6 and python2.7 (and I got the latter installed): $ apt-cache show fabric | grep Dep (HowTos)