ttk error when starting git gui

Hello,

I get the following error when trying to start git gui:

Error in startup script: wrong # args: should be "ttk::style theme use 
theme"
     while executing
"ttk::style theme use"
     (procedure "ttext" line 4)
     invoked from within
"ttext $ui_workdir -background white -foreground black \
         -borderwidth 0 \
         -width 20 -height 10 \
         -wrap none \
         -takefocus 1 -highlightthickness 1\
         ..."
     (file 
"/home/dshrader/opt/toss2/common/git/2.12.2/libexec/git-core/git-gui" 
line 3190)

I get this error with the latest released version 2.12.2. Two older git versions are also available on this system, and neither has this issue. Those older versions are 1.7.1 and 2.3.3. I don't see a call to ttext in those corresponding git-gui executables, so that is probably why they work.

Here are the steps to reproduce:

1) cd to existing git repository
2) run 'git gui' (no gui comes up, and the error is printed in the terminal)

I'm running on a RHEL6 based system. Do I have an insufficient version of whatever git gui uses for graphics in the later versions of git? When I try 2.12.2 on my personal workstation running Fedora 25, I don't see the same issue.

Thank you very much for your time, David