Dune shows "Source files changed, restarting current build" for more than 30s

[jchavarri]

In our build, after changing files, sometimes the Source files changed, restarting current build (xxx/yyy) shows, but the number_of_rules_executed / xxx and number_of_rules_discovered / yyy values continue to increase. It doesn't seem that Dune is actually running any external commands by these rules, just still discovering and processing them.

After a while (some cases can take > 30 seconds) the counters restart at 0 and the build recommences.

This behavior is quite confusing as a user. Is this the expected behavior?