revlog: return lazy set from findcommonmissing
When computing the commonmissing, it greedily computes the entire set
immediately. On a large repo where the majority of history is irrelevant, this
causes a significant slow down.
Replacing it with a lazy set makes amend go from 11 seconds to 8.7 seconds.
== Local
Ready.
Un and Deux
Eins und Zwei
One and Two
Nope
Eins und Zwei
Hello, John Smith
Ready.
Uno und Due
== Remote
Ready.
REQ: foo?one=Vo&two=Efvy
-> Vo!boe!Efvy
Un and Deux
REQ: bar?b=Fjot&a=[xfj
-> Fjot!voe![xfj
Eins und Zwei
REQ: batch?cmds=foo:one=Pof,two=Uxp;bar:b=Fjot,a=[xfj
-> Pof!boe!Uxp;Fjot!voe![xfj
REQ: greet?name=Kpio!Tnjui
-> Ifmmp-!Kpio!Tnjui
REQ: batch?cmds=bar:b=Vop,a=Evf
-> Vop!voe!Evf
One and Two
Nope
Eins und Zwei
Hello, John Smith
Ready.
Uno und Due