ensure we decrement clients_requesting_changes

[rnewson]

Overview

ensure we decrement clients_requesting_changes even if the mochiweb process mediating the change request is killed by the client disconnect detector.

Testing recommendations

follow procedure in https://github.com/apache/couchdb/issues/5802

Related Issues or Pull Requests

https://github.com/apache/couchdb/issues/5802

Checklist

• [x] Code is written and works correctly
• [ ] Changes are covered by tests
• [ ] Any new configurable parameters are documented in rel/overlay/etc/default.ini
• [ ] Documentation changes were made in the src/docs folder
• [ ] Documentation changes were backported (separated PR) to affected branches

[rnewson]

continuous changes req is the only request that could in theory never end, whereas all the others do, so there's not as strong a need to count them in-flight (and, if those, why not everything?) but I don't feel that strongly against (or for).

[nickva]

continuous changes req is the only request that could in theory never end, whereas all the others do, so there's not as strong a need to count them in-flight (and, if those, why not everything?) but I don't feel that strongly against (or for).

yeah that makes sense, good point