absorb: preserve changesets which were already empty Most commands in Mercurial (commit, rebase, absorb itself) don’t create empty changesets or drop them if they become empty. If there’s a changeset that’s empty, it must be a deliberate choice of the user. At least it shouldn’t be absorb’s responsibility to prune them. The fact that changesets that became empty during absorb are pruned, is unaffected by this. This case was found while writing patches which make it possible to configure absorb and rebase to not drop empty changesets. Even without having such config set, I think it’s valuable to preserve changesets which were already empty.

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  $ hg init

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  $ touch a

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  $ unset HGUSER

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  $ echo "[ui]" >> .hg/hgrc

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  $ echo "username= foo" >> .hg/hgrc

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  $ echo "          bar1" >> .hg/hgrc

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  $ hg ci -Am m

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  adding a

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  abort: username 'foo\nbar1' contains a newline

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  [255]

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  $ rm .hg/hgrc

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  $ HGUSER=`(echo foo; echo bar2)` hg ci -Am m

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  adding a

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  abort: username 'foo\nbar2' contains a newline

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  [255]

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  $ hg ci -Am m -u "`(echo foo; echo bar3)`"

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  adding a

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  transaction abort!

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  rollback completed

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  abort: username 'foo\nbar3' contains a newline!

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  [255]

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