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+.TH dgit 7 "" "Debian Project" "dgit"
+dgit \- principles of operation
+.B dgit
+treats the Debian archive as a version control system, and
+bidirectionally gateways between the archive and git. The git view of
+the package can contain the usual upstream git history, and will be
+augmented by commits representing uploads done by other developers not
+using dgit. This git history is stored in a canonical location known
+.B dgit-repos
+which lives outside the Debian archive (currently, on Alioth).
+You may use any suitable git workflow with dgit, provided you
+satisfy dgit's requirements:
+dgit maintains a pseudo-remote called
+.BR dgit ,
+with one branch per suite. This remote cannot be used with
+plain git.
+.B dgit-repos
+repository for each package contains one ref per suite named
+\fBrefs/dgit/\fR\fIsuite\fR. These should be pushed to only by
+dgit. They are fast forwarding. Each push on this branch
+corresponds to an upload (or attempted upload).
+However, it is perfectly fine to have other branches in dgit-repos;
+normally the dgit-repos repo for the package will be accessible via
+the remote name `origin'.
+dgit push will also (by default) make signed tags called
+.BI debian/ version
+and push them to dgit-repos, but nothing depends on these tags
+dgit push can operate on any commit which is a descendant of the
+current dgit/suite tip in dgit-repos.
+Uploads made by dgit contain an additional field
+.B Dgit
+in the source package .dsc. (This is added by dgit push.)
+This specifies a commit (an ancestor of the dgit/suite
+branch) whose tree is identical to the unpacked source upload.
+Uploads not made by dgit are represented in git by commits which are
+synthesised by dgit. The tree of each such commit corresponds to the
+unpacked source; there is an origin commit with the contents, and a
+psuedo-merge from last known upload - that is, from the contents of
+the dgit/suite branch.
+dgit expects repos that it works with to have a
+.B dgit
+remote. This refers to the well-known dgit-repos location
+(currently, the dgit-repos project on Alioth). dgit fetch updates
+the remote tracking branch for dgit/suite.
+dgit does not (currently) represent the orig tarball(s) in git. The
+orig tarballs are downloaded (by dgit clone) into the parent
+directory, as with a traditional (non-gitish) dpkg-source workflow.
+You need to retain these tarballs in the parent directory for dgit
+build and dgit push.
+dgit repositories could be cloned with standard (git) methods. The
+only exception is that for sourcefull builds / uploads the orig
+tarball(s) need to be present in the parent directory.
+To a user looking at the archive, changes pushed using dgit look like
+changes made in an NMU: in a `3.0 (quilt)' package the delta from the
+previous upload is recorded in a new patch constructed by dpkg-source.
+Distros which do not maintain a set of dgit history git repositories
+can still be used in a read-only mode with dgit. Currently Ubuntu
+is configured this way.
+If you are not the maintainer, you do not need to worry about the
+source format of the package. You can just make changes as you like
+in git. If the package is a `3.0 (quilt)' package, the patch stack
+will usually not be represented in the git history.
+For a format `3.0 (quilt)' source package, dgit may have to make a
+commit on your current branch to contain metadata used by quilt and
+This is because `3.0 (quilt)' source format represents the patch stack
+as files in debian/patches/ actually inside the source tree. This
+means that, taking the whole tree (as seen by git or ls) (i)
+dpkg-source cannot represent certain trees, and (ii) packing up a tree
+in `3.0 (quilt)' and then unpacking it does not always yield the same
+dgit will automatically work around this for you when building and
+pushing. The only thing you need to know is that dgit build, sbuild,
+etc., may make new commits on your HEAD. If you're not a quilt user
+this commit won't contain any changes to files you care about.
+You can explicitly request that dgit do just this fixup, by running
+dgit quilt-fixup.
+If you are a quilt user you need to know that dgit's git trees are
+`patches applied packaging branches' and do not contain the .pc
+directory (which is used by quilt to record which patches are
+applied). If you want to manipulate the patch stack you probably want
+to be looking at tools like git-dpm.
+This section is mainly of interest to maintainers who want to use dgit
+with their existing git history for the Debian package.
+Some developers like to have an extra-clean git tree which lacks files
+which are normally found in source tarballs and therefore in Debian
+source packages. For example, it is conventional to ship ./configure
+in the source tarball, but some people prefer not to have it present
+in the git view of their project.
+dgit requires that the source package unpacks to exactly the same
+files as are in the git commit on which dgit push operates. So if you
+just try to dgit push directly from one of these extra-clean git
+branches, it will fail.
+As the maintainer you therefore have the following options:
+Persuade upstream that the source code in their git history and the
+source they ship as tarballs should be identical. Of course simply
+removing the files from the tarball may make the tarball hard for
+people to use.
+One answer is to commit the (maybe autogenerated)
+files, perhaps with some simple automation to deal with conflicts and
+spurious changes. This has the advantage that someone who clones
+the git repository finds the program just as easy to build as someone
+who uses the tarball.
+Have separate git branches which do contain the extra files, and after
+regenerating the extra files (whenever you would have to anyway),
+commit the result onto those branches.
+Provide source packages which lack the files you don't want
+in git, and arrange for your package build to create them as needed.
+This may mean not using upstream source tarballs and makes the Debian
+source package less useful for people without Debian build
+Of course it may also be that the differences are due to build system
+bugs, which cause unintended files to end up in the source package.
+dgit will notice this and complain. You may have to fix these bugs
+before you can unify your existing git history with dgit's.