rxjs 6.3 mergeMap no longer works with Observable from a promise

[menved]

rxjs version 6.3 mergeMap no longer works with an Observable from a promise (compared with version 6.2.2).
The Observable never subscribes.

myObservable
.pipe(
  mergeMap(x =>
     from(Promise.resolve(['test']))
  )
.subscribe()

Environment

• Runtime: Node v10.9.0
• RxJS version: 6.3
• webpack 4.17.1

[cartant]

See #4071 and #4072. Hopefully, this is the same problem - which has been fixed.

[LM-G]

@cartant Hello, there is a problem on the from, if you do something like this

from(SOME_PROMISE).pipe(switchMap(() => SOME_OBSERVABLE)).subscribe(...)

with SOME_OBSERVABLE getting an event in the future, the subscription of SOME_OBSERVABLE is canceled instantly.

[cartant]

@LM-G as stated above, see the failing tests that were fixed in #4072. Said tests used from with promises.

[menved]

Version 6.3.1 has solved the problem :)