Don't build everything in one go

In some cases the build script may focus on something
irrelevant (e.g. old commits or commits in a different branch), which
means that whatever is committed during this process will not be built
until everything is done. By adding a limit we ensure that the process
ends quicker, and when it is restarted it will first work on the most
recent commits.

build.p6

@@ -101,6 +101,7 @@ run ‘git’, ‘--git-dir’, “{REPO-CURRENT}/.git”, ‘--work-tree’, RE
 
 sub process-commit($commit) {
     return if “{ARCHIVES-LOCATION}/$commit.zst”.IO ~~ :e; # already exists
+    return if $++ ≥ 10; # refuse to build too many commits at once
 
     my ($temp-folder,) = tempdir, :!unlink;
     my $build-path   = “{BUILDS-LOCATION}/$commit”.IO.absolute;