sysconf_DATA v. dist_sysconf_DATA

[David Everly]

automake (GNU automake) 1.9.6
autoconf (GNU Autoconf) 2.60
HP-UX omztdv1 B.11.23 U ia64

I have recently discovered this in the manual:

"By default, data files are not included in a distribution. Of course,
you can use the dist_ prefix to change this on a per-variable basis."

So instead of this in Makefile.am:

  sysconf_DATA = $(top_srcdir)/test.txt

I should have used this (because test.txt is not constructed):

  dist_sysconf_DATA = $(top_srcdir)/test.txt

However, I've regularly run 'make distcheck' and it gives no error
with the original sysconf_DATA.  How can this be?