[...]
Making all in python
make[2]: Entering directory `/tmp/exo-0.3.101/python'
(cd .                                                   \
         && /usr/local/bin/pygtk-codegen-2.0                                            \
            --register /usr/local/share/pygtk/2.0/defs/pango-types.defs         \
            --register /usr/local/share/pygtk/2.0/defs/atk-types.defs                   \
            --register /usr/local/share/pygtk/2.0/defs/gdk-types.defs                   \
            --register /usr/local/share/pygtk/2.0/defs/gtk-types.defs                   \
            --override exo.override                                     \
            --prefix exo exo.defs) > xgen-exo.c                         \
        && cp xgen-exo.c exo.c                                          \
        && rm -f xgen-exo.c
  File "/usr/local/share/pygtk/2.0/codegen/codegen.py", line 47
    return name + '_'
                    ^
TabError: inconsistent use of tabs and spaces in indentation
make[2]: *** [exo.c] Error 1
make[2]: Leaving directory `/tmp/exo-0.3.101/python'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/tmp/exo-0.3.101'
make: *** [all] Error 2