stream-clone: disable gc for `_entries_walk` duration The number of small container created turn Python in a gc-frenzy that seriously impact performance. This significantly boost performance. The following number comes from a large private repository using perf::stream-locked-section: base-line: 35.04 seconds prev-change: 24.51 seconds (-30%) this-change: 20.88 seconds (-40% from baseline; -15% from previous changes)

     1

  $ hg init repo

     2

  $ cd repo

     3

  $ echo a > a

     4

  $ hg ci -Am t

     5

  adding a

     6

     7

  $ hg mv a b

     8

  $ hg ci -Am t1

     9

  $ hg debugrename b

    10

  b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3

    11

    12

  $ hg mv b a

    13

  $ hg ci -Am t2

    14

  $ hg debugrename a

    15

  a renamed from b:37d9b5d994eab34eda9c16b195ace52c7b129980

    16

    17

  $ hg debugrename --rev 1 b

    18

  b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3

    19