Xref oddness

[Patrick Mahan <plmahan@gmail.com>]

We have just recently upgraded some of our development machines to Ubuntu
18.04 which includes emacs 25.2 (we were on Ubuntu 16.04 and emacs 24.5).
I notice that emacs 25 brings with it changes to TAGS handling that have
been moved under Xref.  But I am now seeing some odd behavior

Our sysadmins have setup where our home directories and development
directories are on multiple drives but are all symlinked through the same
top-level directory.  For example, my actual home directory is on
/home2/patrick but it is access via /home/patrick (patrick under /home is
sym-linked to /home2/patrick).  The same occurs for our development
directories (/development/patrick is sym-linked to /development5/patrick).
Now since our development directories are setup as multiple directories, I
was using the following  method for finding TAGS files -

(setq tags-table-list (list "./" "../"
                                (concat (getenv "WORK") "/src/lib")
                                (concat (getenv "WORK") "/src/bin")
                                (concat (getenv "WORK") "/src/include")
                                (concat (getenv "WORK") "/src")))

WORK is defined as the top of my current development sandbox and changes as
I jump between sandboxes.

This worked great in 24.5, but now in 25.2 I am seeing multiple definitions
everytime I try to find a tag (M-.) (which is 'xref-find-definitions').
One for '/development5/..." and one for "/development/...".

Now that documentation mentions something about 'xref-etags-mode' as a
minor mode, but I cannot seem to invoke that mode in emacs.  Is there a way
to fix this in Xref? Or should I just go back to redefining those keys to
the old 'find-tag' et.al.?

Thanks,

Patrick