cvsimport: skip commits that are too recent

With this patch, cvsimport will skip commits made
in the last 10 minutes. The recent-ness test is of
5 minutes + cvsps fuzz window (5 minutes default).

When working with a CVS repository that is in use,
importing commits that are too recent can lead to
partially incorrect trees. This is mainly due to

 - Commits that are within the cvsps fuzz window may later
   be found to have affected more files.

 - When performing incremental imports, clock drift between
   the systems may lead to skipped commits.

This commit helps keep incremental imports of in-use
CVS repositories sane.

Signed-off-by: Martin Langhoff <martin@catalyst.net.nz>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git-cvsimport.perl

@@ -129,6 +129,11 @@ ($)
 	push (@mergerx, qr/$opt_M/);
 }
 
+# Remember UTC of our starting time
+# we'll want to avoid importing commits
+# that are too recent
+our $starttime = time();
+
 select(STDERR); $|=1; select(STDOUT);
 
 
@@ -824,6 +829,15 @@ sub commit {
 			$state = 11;
 			next;
 		}
+		if ( $starttime - 300 - (defined $opt_z ? $opt_z : 300) <= $date) {
+			# skip if the commit is too recent
+			# that the cvsps default fuzz is 300s, we give ourselves another
+			# 300s just in case -- this also prevents skipping commits
+			# due to server clock drift
+			print "skip patchset $patchset: $date too recent\n" if $opt_v;
+			$state = 11;
+			next;
+		}
 		if (exists $ignorebranch{$branch}) {
 			print STDERR "Skipping $branch\n";
 			$state = 11;