view mercurial/help/diffs.txt @ 18656:8eb3408bf005

import: don't rollback on failed import --exact (issue3616)

The checkexact() helper function was calling repo.rollback() from inside
an open transaction. In addition to being insane, this is unnecessary
because import will release the transaction on an exception.

It turns out that this has been broken since the feature was first
introduced, first released in v1.0:

changeset:   4263:47ba52121433
user:        Brendan Cully <[e-mail]>
date:        Thu Mar 22 10:44:59 2007 -0700
files:       mercurial/commands.py mercurial/patch.py
description:
Add import --exact.
When this option is set, import will apply the patch (which must
be generated by export) to the parents specified in the patch,
and check that the node produced by the patch matches the node
ID in the patch.

Mercurial's default format for showing changes between two versions of
a file is compatible with the unified format of GNU diff, which can be
used by GNU patch and many other standard tools.

While this standard format is often enough, it does not encode the
following information:

- executable status and other permission bits
- copy or rename information
- changes in binary files
- creation or deletion of empty files

Mercurial also supports the extended diff format from the git VCS
which addresses these limitations. The git diff format is not produced
by default because a few widespread tools still do not understand this
format.

This means that when generating diffs from a Mercurial repository
(e.g. with :hg:`export`), you should be careful about things like file
copies and renames or other things mentioned above, because when
applying a standard diff to a different repository, this extra
information is lost. Mercurial's internal operations (like push and
pull) are not affected by this, because they use an internal binary
format for communicating changes.

To make Mercurial produce the git extended diff format, use the --git
option available for many commands, or set 'git = True' in the [diff]
section of your configuration file. You do not need to set this option
when importing diffs in this format or using them in the mq extension.