upon inspection, it seems that the ebuild leaves out linking to python, and does not build tclthreads.c. to examine: launch tclsh: % package require tclpython couldn't load file "/usr/lib64/tclpython/tclpython.so.4.1": /usr/lib64/tclpython/tclpython.so.4.1: undefined symbol: Py_NoSiteFlag if -lpython$(python_get_version) is passed, then this undefined symbol is not encountered. However in my build of tcl (which is USE=threads), I get further undefined symbols unless I build tclthreads.c in also.
Which version of tclpython? emerge --info?
4.1-r2. Sorry, I got distracted from the bug. I had meant to also attach a diff that fixes it for me (and also should fix bug 312217)
Created attachment 226669 [details, diff] tclpython-4.1-r2.ebuild.patch
Thanks for the patch, fixed in the tree.