largefiles: make linear update set unsure largefiles normal if unchanged
'hg update' would hash all 'unsure' largefiles before performing the merge. It
would update the standins but not detect the very common case where the
largefile never had been changed by the user but just had been marked with an
invalid dirstate mtime to make sure any changes done by the user in the same
second would be detected. The largefile would remain in that state and would
have to be hashed again next time even though it still not had been changed.
Sad trombone.
Instead, for largefiles listed as 'unsure' or 'modified', after updating the
standin with the actual hash, mark the largefile as normal if it turns out to
not be modified relative to the revision in the parent revision. That will
prevent it from being hashed again next time.
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.