dpkg: Fix filter subpattern debug format string

Use a string precision instead of a field width, which was causing the
output to be just blanks with the length of the subpattern.

debian/changelog

@@ -25,6 +25,8 @@ dpkg (1.16.9) UNRELEASED; urgency=low
   * Use a hash instead of a ref to a hash for keys() in Dpkg::BuildFlags
     get_feature_areas(). This causes compilation failures with older perl
     versions, which can be an issue with partial upgrades.
+  * Fix filter subpattern debug output format string to print an actual
+    value instead of just blanks.
 
   [ Updated programs translations ]
   * Czech (Miroslav Kure).

src/filters.c

@@ -115,7 +115,7 @@ filter_should_skip(struct tar_entry *ti)
 				path_len = strlen(f->pattern);
 
 			debug(dbg_eachfiledetail,
-			      "filter subpattern '%*.s'", path_len, f->pattern);
+			      "filter subpattern '%.*s'", path_len, f->pattern);
 
 			if (strncmp(&ti->name[1], f->pattern, path_len) == 0) {
 				debug(dbg_eachfile, "filter reincluding %s",