* Fix two calls to chdir without proper error checking.
* Fix a couple of bugs in error reporting.
* Fix up .orig detection to be less trustful of (ambiguous) filenames.
+ * Fix up .orig detection to correctly allow exactly the right
+ .orig-comp components accorging to dpkg-source(1).
+ * Fix up .orig detection to handle .asc's (and other signatures)
+ of .orig components the same way as their tarballs.
Test suite:
* When sbuild fails, do not crash due to sed not finding the log