dpkg-source: Do not state in --help there is a default substvar file

debian/changelog

@@ -128,6 +128,8 @@ dpkg (1.15.1) UNRELEASED; urgency=low
   * Remove deprecated status on substvars for dpkg-source dpkg-genchanges,
     and stop producing warnings.
   * Make deprecated dpkg-scanpackages --udeb option produce a warning.
+  * Change dpkg-source --help output to state there's no default substvar
+    file to match reality.
 
   [ Frank Lichtenheld ]
   * Dpkg::Version: Remove unnecessary function next_elem which just

scripts/dpkg-source.pl

@@ -372,7 +372,7 @@ Build options:
   -l<changelogfile>        get per-version info from this file.
   -F<changelogformat>      force change log format.
   -V<name>=<value>         set a substitution variable.
-  -T<varlistfile>          read variables here, not debian/substvars.
+  -T<varlistfile>          read variables here.
   -D<field>=<value>        override or add a .dsc field and value.
   -U<field>                remove a field.
   -q                       quiet mode.