tests/test-update-reverse.t

match: avoid translating glob to matcher multiple times for large sets

For hgignore with many globs, the resulting regexp might not fit under the 20K
length limit. So the patterns need to be broken up in smaller pieces.

Before this change, the logic was re-starting the full process from scratch
for each smaller pieces, including the translation of globs into regexp.
Effectively doing the work over and over.

If the 20K limit is reached, we are likely in a case where there is many such
glob, so exporting them is especially expensive and we should be careful not
to do that work more than once.

To work around this, we now translate glob to regexp once and for all. Then,
we assemble the resulting individual regexp into valid blocks.

This raises a very significant performance win for large `.hgignore file`:

Before: ! wall 0.153153 comb 0.150000 user 0.150000 sys 0.000000 (median of 66)
After:  ! wall 0.059793 comb 0.060000 user 0.060000 sys 0.000000 (median of 100)

  $ hg init

  $ touch a
  $ hg add a
  $ hg commit -m "Added a"

  $ touch main
  $ hg add main
  $ hg commit -m "Added main"
  $ hg checkout 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

'main' should be gone:

  $ ls
  a

  $ touch side1
  $ hg add side1
  $ hg commit -m "Added side1"
  created new head
  $ touch side2
  $ hg add side2
  $ hg commit -m "Added side2"

  $ hg log
  changeset:   3:91ebc10ed028
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added side2
  
  changeset:   2:b932d7dbb1e1
  parent:      0:c2eda428b523
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added side1
  
  changeset:   1:71a760306caf
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added main
  
  changeset:   0:c2eda428b523
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added a
  

  $ hg heads
  changeset:   3:91ebc10ed028
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added side2
  
  changeset:   1:71a760306caf
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added main
  
  $ ls
  a
  side1
  side2

  $ hg update --debug -C 1
  resolving manifests
   branchmerge: False, force: True, partial: False
   ancestor: 91ebc10ed028+, local: 91ebc10ed028+, remote: 71a760306caf
   side1: other deleted -> r
  removing side1
   side2: other deleted -> r
  removing side2
   main: remote created -> g
  getting main
  1 files updated, 0 files merged, 2 files removed, 0 files unresolved

  $ ls
  a
  main