Description of problem:
Since https://src.fedoraproject.org/rpms/bash/c/739b272e5f5d10cf27a847a44d09eb7f4b6ec89b?branch=f29 , User PATH is prepended to $PATH every time ~/.bashrc is sourced. This includes the login phase and when the user runs bash inside the session. The result is two duplicate user PATH entries in $PATH, gets even more with nested bash sessions. 
This does no harm, but may confuse users.

Version-Release number of selected component (if applicable):
bash-4.4.23-5.fc29.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Open a graphical session with startx or a DM. In my case it's KDE/SDDM. Not tested on gdm/GNOME(Wayland)
2. Open a terminal emulator (must not use d-bus activation)
3. echo $PATH

Actual results:
$ echo $PATH
/home/username/.local/bin:/home/username/bin:/home/username/.local/bin:/home/username/bin:/usr/lib64/ccache:/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin

Expected results:
There shouldn't be duplicate entries in $PATH.

Additional info:
Generally I think it's still better to set $PATH inside ~/.bash_profile. This should work for all applications inside the session's scope unit, as long as default shell is bash, but not for systemd user services.
Another partial fix for display managers is to check whether bash is interactive before sourcing ~/.bashrc in ~/.bash_profile, since /etc/X11/xinit/Xsession runs bash non-interactively.