Let the block of Fbe.repeatedly read back what it wrote in the same run

[Thayorns]

The object that Fbe.repeatedly yields sent every write to a private Hash and every read to the stored marker, so the block could not read back a property it had just set. On the first run the read raised, and since the block failed, when was never written and every later run failed the same way; on a later run the read returned the value of the previous run.

A read now looks at what the block has written in this run first and returns its first value, the way a fact answers a getter. Only when the block has not written that property does the read go to the stored marker, so a property kept from the previous run is still visible.

Three tests read through the proxy: right after writing on the first run, right after writing on a later run, and a property written only in the previous run.

Fbe.repeatedly was already at 49.7 of the 50 allowed by Metrics/AbcSize, and the read needs a lookup and a fallback, so the method now carries # rubocop:disable Metrics/AbcSize, as Fbe.fb, Fbe.overwrite and Fbe.pmp do.

Closes #1246

[Thayorns]

@yegor256 take a look please, happy to clarify anything about the change.