I'm also having this error when doing make install. (as root)
test -z "/home/sentri/mangos/sql/updates" || /bin/mkdir -p "/home/sentri/mangos/sql/updates"
/usr/bin/install -c -m 644 '../../../sql/updates/README' '/home/sentri/mangos/sql/updates/README'
/usr/bin/install: "../../../sql/updates/README" and "/home/sentri/mangos/sql/updates/README" are the same file
#### several lines like above ####
make[3]: *** [install-pkgdataDATA] Error 1
make[3]: Leaving directory `/home/sentri/mangos/objdir/sql/updates'
make[2]: *** [install-am] Error 2
make[2]: Leaving directory `/home/sentri/mangos/objdir/sql/updates'
make[1]: *** [install-recursive] Error 1
make[1]: Leaving directory `/home/sentri/mangos/objdir/sql'
make: *** [install-recursive] Error 1
(rough translation)
EDIT: Solved, just ran ./configure and make again and it worked.