(which might not be faithful to dgit's invariants)
or previous non-Dgit uploads
(which would not provide a very rich history).
+
+git represents only file executability.
+git does not represent empty directories,
+or any leaf objects other than plain files and symlinks.
+The behaviour of Debian source package formats
+on objects with unusual permissions is complicated.
+Some pathological Debian source packages will no longer build
+if empty directories are pruned
+(or if other things not reproduced by git are changed).
+Such sources cannot be worked with properly in git,
+and therefore not with dgit either.
.SH READ-ONLY DISTROS
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
and
.B dgit setup-gitattributes
in dgit(1).
+
+Note that dgit does not disable gitattributes
+unless they would actually interfere with your work on dgit branches.
+In particular, gitattributes which affect
+.B git archive
+are not disabled,
+so .origs you generate by hand can be wrong.
+You should consider using
+.B git-deborig (1)
+which gets this right, suppressing the attributes.
.SH PACKAGE SOURCE FORMATS
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
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.
+Simply commiting to source files
+(whether in debian/ or not, but not to patches)
+will result in a branch that dgit quilt-fixup can linearise.
+Other kinds of changes,
+including editing patches or merging,
+cannot be handled this way.
+
You can explicitly request that dgit do just this fixup, by running
dgit quilt-fixup.
`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.
+to be looking at tools like
+git-debrebase, gbp pq, or git-dpm.
+
+.SS quilt fixup error messages
+When dgit's quilt fixup fails, it prints messages like this:
+
+.EX
+dgit: base trees orig=5531f03d8456b702eab6 o+d/p=135338e9cc253cc85f84
+dgit: quilt differences: src: == orig ## gitignores: == orig ##
+dgit: quilt differences: HEAD ## o+d/p HEAD ## o+d/p
+starting quiltify (multiple patches, linear mode)
+
+dgit: error: quilt fixup cannot be linear. Stopped at:
+dgit: 696c9bd5..84ae8f96: changed debian/patches/test-gitignore
+.EE
+
+.TP
+.B orig
+is an import of the .orig tarballs dgit found,
+with the debian/ directory from your HEAD substituted.
+This is a git tree object, not a commit:
+you can pass its hash to git-diff but not git-log.
+
+.TP
+.B o+d/p
+is another tree object,
+which is the same as orig
+but with the patches from debian/patches applied.
+
+.TP
+.B HEAD
+is of course your own git HEAD.
+
+.TP
+.B quilt differences
+shows whether each of the these trees differs from the others
+(i) in upstream files excluding .gitignore files;
+(ii) in upstream .gitignore files.
+.B ==
+indicates equality;
+.B ##
+indicates inequality.
+.LP
+dgit quilt-fixup --quilt=linear walks commits
+backwards from your HEAD
+trying to construct a linear set of additional patches,
+starting at the end.
+It hopes to eventually find an ancestor
+whose tree is identical to o+d/p in all upstream files.
+
+In the error message,
+696c9bd5..84ae8f96
+is the first commit child-parent edge
+which cannot be sensibly be
+either ignored, or turned into a patch in debian/patches.
+In this example, this is because
+it itself changes files in debian/patches,
+indicating that something unusual is going on
+and that continuing is not safe.
+But you might also see other kinds of troublesome commit or edge.
+
+Your appropriate response depends on the cause and the context.
+If you have been freely merging your git branch
+and do not need need a pretty linear patch queue,
+you can use
+.B --quilt=smash
+(or use the
+.B 1.0
+or
+.B single-debian-patch
+source formats; see
+.BR dpkg-source(1) .)
+If you want a pretty linear series,
+and this message is unexpected,
+it can mean that you have unwittingly committed changes
+that are not representable by dpkg-source (such as some mode changes).
+Or maybe you just forgot a necessary
+.B --quilt=
+option.
+
+Finally,
+this problem can occur if you have provided
+Debian git tooling such as git-debrebase, git-dpm or git-buildpackage
+with upstream git commit(s) or tag(s)
+which are not 100% identical to your orig tarball(s).
.SH SPLIT VIEW QUILT MODE
When working with git branches intended
for use with the `3.0 (quilt)' source format
~ianmdlvl / dgit.git / blobdiff