tests/test-rebase-abort.t

revlog: improve delta generation heuristics for generaldelta

Without this change, pulls (and clones) into a generaldelta repository could
generate very inefficient revlogs, the size of which could be at least twice
the original size.

This was caused by the generated delta chains covering too large distances,
causing new chains to be built far too often. This change addresses the
problem by forcing a delta against second parent or against the previous
revision, when the first parent delta is in danger of creating a long chain.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > graphlog=
  > rebase=
  > 
  > [alias]
  > tglog = log -G --template "{rev}: '{desc}' {branches}\n"
  > EOF


  $ hg init a
  $ cd a

  $ echo c1 > common
  $ hg add common
  $ hg ci -m C1

  $ echo c2 >> common
  $ hg ci -m C2

  $ echo c3 >> common
  $ hg ci -m C3

  $ hg up -q -C 1

  $ echo l1 >> extra
  $ hg add extra
  $ hg ci -m L1
  created new head

  $ sed -e 's/c2/l2/' common > common.new
  $ mv common.new common
  $ hg ci -m L2

  $ hg tglog
  @  4: 'L2'
  |
  o  3: 'L1'
  |
  | o  2: 'C3'
  |/
  o  1: 'C2'
  |
  o  0: 'C1'
  

Conflicting rebase:

  $ hg rebase -s 3 -d 2
  merging common
  warning: conflicts during merge.
  merging common failed!
  abort: unresolved conflicts (see hg resolve, then hg rebase --continue)
  [255]

Abort:

  $ hg rebase --abort
  saved backup bundle to $TESTTMP/a/.hg/strip-backup/*-backup.hg (glob)
  rebase aborted

  $ hg tglog
  @  4: 'L2'
  |
  o  3: 'L1'
  |
  | o  2: 'C3'
  |/
  o  1: 'C2'
  |
  o  0: 'C1'
  
  $ cd ..


Constrcut new repo:

  $ hg init b
  $ cd b

  $ echo a > a
  $ hg ci -Am A
  adding a

  $ echo b > b
  $ hg ci -Am B
  adding b

  $ echo c > c
  $ hg ci -Am C
  adding c

  $ hg up -q 0

  $ echo b > b
  $ hg ci -Am 'B bis'
  adding b
  created new head

  $ echo c1 > c
  $ hg ci -Am C1
  adding c

Rebase and abort without generating new changesets:

  $ hg tglog
  @  4: 'C1'
  |
  o  3: 'B bis'
  |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ hg rebase -b 4 -d 2
  merging c
  warning: conflicts during merge.
  merging c failed!
  abort: unresolved conflicts (see hg resolve, then hg rebase --continue)
  [255]

  $ hg tglog
  @  4: 'C1'
  |
  o  3: 'B bis'
  |
  | @  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ hg rebase -a
  rebase aborted

  $ hg tglog
  @  4: 'C1'
  |
  o  3: 'B bis'
  |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'