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  • Anton Shestakov's avatar
    pick: remove transaction on the whole command (issue6037) · 313565dd75e3
    Anton Shestakov authored
    At its core, pick is a pretty straightforward and well-behaving command, it
    uses functions already in core hg, it checks that wdir is clean and that
    changeset to pick is not public, it checks if there happen to be merge
    conflicts and can be --continue'd later, etc.
    
    It is very similar to graft in core (it also uses mergemod.graft function), but
    it obsoletes the original changeset. However, graft does not experience this
    incorrect behavior from issue 6037.
    
    What happens in the test case for this issue when we pick a revision that
    touches both "a" and "b": mergemod.graft() takes the original changeset and
    tries to apply it to the wdir, which results in "b" being marked as newly added
    and ready to be committed, "a" updated with the new content and being marked as
    modified, but "a" also has conflicts. Pick correctly notices this and saves its
    state before asking for user intervention. So far so good. However, when the
    command raises InterventionRequired to print a user-facing message and exit
    while being wrapped in repo.transaction() context manager, the latter partially
    undoes what mergemod.graft() did: it unmarks "b" as added. And when user
    continues pick, "b" is therefore not tracked and is not included in the
    resulting commit.
    
    The transaction is not useful here, because it doesn't touch wdir (it's still
    dirty), it doesn't remove pickstate (and other commands will refuse to work
    until pick --abort or --continue), it just makes "b" untracked.
    
    The solution is to use repo.transaction() only to wrap code that writes data to
    hg store in the final stages of the command after all checks have passed and is
    not expected to fail on trivial cases like merge conflicts. For example,
    committing the picked changeset. But since pick uses repo.commit() for that,
    and because that function already uses a transaction, wrapping it in another
    transaction doesn't make sense.
    313565dd75e3
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