(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
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.
+.SH FILE EXECUTABILITY
+Debian source package formats
+do not always faithfully reproduce
+changes to executability.
+But dgit insists that the result of dgit clone is identical
+(as far as git can represent - see Limitations, above)
+to the result of dpkg-source -x.
+
+So files that are executable in your git tree
+must be executable in the result of dpkg-source -x
+(but often aren't).
+If a package has such troublesome files,
+they have to be non-executable in dgit-compatible git branches.
.SH FORMAT 3.0 (QUILT)
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