this should be obvious :
rowan@hal ~ $ cat /usr/lib/tls1.50/pkgIndex.tcl
package ifneeded tls 1.50 "[list load [file join $dir .. libtls1.50.so] ] ; [list source [file join $dir tls.tcl] ]"
rowan@hal ~ $ ls /usr/lib/tls1.50
libtls-1.50.so pkgIndex.tcl tls.tcl
as you can see, the pkgIndex.tcl tries to load "$dir/../libtls1.50.so" which would be /usr/lib/tls1.50/../libtls1.50.so which is /usr/lib/libtls1.50.so but the file is in /usr/lib/tls1.50/libtls-1.50.so
so you would need to remove the '..' from the [file join] in pkgIndex.tcl and add the dash to change libtls1.50.so into libtls-1.50.so
or check that the file exists (maybe as a symlink).
Obviously, your tls installation was badly done, I don't remember which distro had that, but there's a bad package out there.
you could also try doing the 'load' and 'source' manually to see if anything is wrong. or do a 'ldd' on libtls to see if any dependency is missing.. and lastly, try to delete the one in plugins, it might cause a version conflict.