tests/test-update-reverse.t

transaction: support cache file in backupentries

We do not want to abort if anything wrong happen while handling a cache file.
Cache file have way to be invalidated and if old/bad version stay no
misbehavior will happen. Proper value will eventually be computed and the wrong
will be righten.

This changeset use the transaction reporter (usually writing on stderr) to write
details about failed cache handling. This will only apply to write operation
using a transaction. The usual update during read only operation will stay a
debug message.

I was on the way to bring these message back to debug level when I realised it
could be a feature. People with write access to the repository are likely to
have the power to fix error related to cache (and it is valuable to fix them).
So let the things as is for now.

  $ 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
  updating: side2 2/3 files (66.67%)
   main: remote created -> g
  getting main
  updating: main 3/3 files (100.00%)
  1 files updated, 0 files merged, 2 files removed, 0 files unresolved

  $ ls
  a
  main