dry_run.patch

diff -u -r -P ./mainline/src/build.cc ./patched/src/build.cc
--- ./mainline/src/build.cc	2011-11-14 09:34:51.415514600 +0000
+++ ./patched/src/build.cc	2011-11-14 09:33:40.936364600 +0000
@@ -620,7 +620,7 @@
       for (vector<Node*>::iterator i = edge->outputs_.begin();
            i != edge->outputs_.end(); ++i) {
         TimeStamp new_mtime = disk_interface_->Stat((*i)->path());
-        if ((*i)->mtime() == new_mtime) {
+        if ((*i)->mtime() == new_mtime && !config_.dry_run) {
           // The rule command did not change the output.  Propagate the clean
           // state through the build graph.
           // Note that this also applies to nonexistent outputs (mtime == 0).