Cannot execute facets_update_8006 due to missing dependencies block_content_update_8600 (also fails with core 8.5)

There is a similiar problem with core 8.5:

Using drupal core 8.5 I cannot execute the facets_update_8006().

drush updatedb shows the update info "Update facet blocks configuration with a block id used for AJAX support" (taken from the description of facets_update_8006) but the function is never called.

I digged a little deeper and found:

• the dependency check introduced in #3006741 checks for the update of core module block_content 8600 (facets_update_dependencies())
• update block_content 8600 is part of drupal 8.6 but not of 8.5
  (update number 8600 -> core 8.6)
• So facets_update_dependencies() blocks the execution of facets_update_8006() until block_content update 8600 is performed - which is never!
• So facets_update_8006() is never executed!
• and the next drush updatedb will show facets_update_8006 again and again!

See hook_update_N() and hook_update_dependencies().

I think we need to check drupal version too.
Patch attached.

P.S. I did not find this issue at first, so I created a new one (#3027801). Closing that one now.

Patch #4 without file mode change.

Also updated description.

Looks good, maybe we should introduce a dependency on core 8.6 in the same patch as well?

@borisson_ : the module is running with 8.5 so I do not think we should add an 8.6 dependency.
It's just if you have 8.6 (and block_content is enabled), than you need to execute update block_content 8600 before update facets_update_8006.

Committed and pushed.