Closes:#833025.
* Better error message if HEAD contains changes unrepresentable
by `3.0 (quilt)'. Closes:#834618.
+ * Much better error message when HEAD and .dsc do not match.
+ Closes:#809516.
Infrastructure:
* Better error handling in dgit-repos-policy-debian.
etc. Closes:#827892.
* Allow local git config options to override user-global ones,
as is proper. Closes:#835858.
+ * Get sense of failed clone failed cleanup error reporting check
+ correct. Closes:#796773.
Test suite:
* When sbuild fails, do not crash due to sed not finding the log