Should be an issue when trying to build the package too? The packages are codependent, so when you try installing them in a clean chroot you get this:

$ arch-nspawn /var/lib/archbuild/extra-x86_64/eschwartz pacman -S python2-zbar
resolving dependencies...
looking for conflicting packages...
warning: dependency cycle detected:
warning: harfbuzz will be installed before its freetype2 dependency

Packages (61) atk-2.30.0-1 avahi-0.7+18+g1b5f401-1 cairo-1.16.0-2 desktop-file-utils-0.23+4+g92af410-1 fontconfig-2:2.13.1+12+g5f5ec56-1
freetype2-2.9.1-1 fribidi-1.0.5-1 gdk-pixbuf2-2.38.0-1 graphite-1:1.3.13-1 gtk-update-icon-cache-3.24.5-1 gtk2-2.24.32-1
harfbuzz-2.3.1-2 hicolor-icon-theme-0.17-1 jasper-2.0.14-1 lcms2-2.9-1 libcups-2.2.10-2 libdaemon-0.14-4 libdatrie-0.2.12-1
libglade-2.6.4-6 libice-1.0.9-2 libjpeg-turbo-2.0.2-1 liblqr-0.4.2-2 libmagick-7.0.8.28-1 libnsl-1.2.0-1 libpng-1.6.36-1
libraqm-0.5.0-1 librsvg-2:2.44.13-1 libsm-1.2.3-1 libthai-0.1.28-1 libtiff-4.0.10-1 libx11-1.6.7-1 libxau-1.0.9-1
libxcb-1.13.1-1 libxcomposite-0.4.4-3 libxcursor-1.1.15-1 libxdamage-1.1.4-3 libxdmcp-1.1.2-2 libxext-1.3.3-2 libxfixes-5.0.3-2
libxft-2.3.2-2 libxi-1.7.9-2 libxinerama-1.1.4-1 libxrandr-1.5.1-2 libxrender-0.9.10-2 libxv-1.0.11-2 lzo-2.10-2
pango-1:1.42.4-1 pixman-0.38.0-2 pygobject2-devel-2.28.7-2 pygtk-2.24.0-8 python2-2.7.15-4 python2-cairo-1.18.0-1
python2-gobject2-2.28.7-2 shared-mime-info-1.12-1 sysfsutils-2.1.0-10 v4l-utils-1.16.3-1 xcb-proto-1.13-2 xorgproto-2018.4-1
zbar-0.21-1 zbar-gtk-0.21-1 python2-zbar-0.21-1

Total Installed Size: 195.71 MiB

:: Proceed with installation? [Y/n]
(61/61) checking keys in keyring [####################################################] 100%
(61/61) checking package integrity [####################################################] 100%
(61/61) loading package files [####################################################] 100%
(61/61) checking for file conflicts [####################################################] 100%
error: failed to commit transaction (conflicting files)
/etc/dbus-1/system.d/org.linuxtv.Zbar.conf exists in both 'zbar' and 'zbar-gtk'
/etc/dbus-1/system.d/org.linuxtv.Zbar.conf exists in both 'zbar' and 'python2-zbar'
/etc/dbus-1/system.d/org.linuxtv.Zbar.conf exists in both 'zbar-gtk' and 'python2-zbar'
Errors occurred, no packages were upgraded.

This is happening with the zbar-qt package as well.