dh: Skips running commands that it can tell do nothing.

This is determined by the presence of special PROMISE directives within
commands that provide a high-level description of the command.

Note that when dh is passed additional debhelper options, it cannot tell if
these change the behavior of commands, and so it stops skipping any
commands.

1 files changed, 2 insertions, 0 deletions

diff --git a/dh_installifupdown b/dh_installifupdown
index 2ea74f43..7b7c2ecf 100755
--- a/dh_installifupdown
+++ b/dh_installifupdown
@@ -52,6 +52,8 @@ as the package name.
 
 init();
 
+# PROMISE: DH NOOP WITHOUT if-pre-up if-up if-down if-post-down
+
 foreach my $package (@{$dh{DOPACKAGES}}) {
 	my $tmp=tmpdir($package);