backportpackage: Use absolute path of workdir when test-building.

backportpackage

@@ -245,6 +245,8 @@ def do_build(workdir, dsc, release, builder, update):
         if 0 != builder.update(release):
             sys.exit(1)
 
+    # builder.build is going to chdir to buildresult:
+    workdir = os.path.realpath(workdir)
     return builder.build(os.path.join(workdir, dsc),
                          release,
                          os.path.join(workdir, "buildresult"))

debian/changelog

@@ -30,6 +30,7 @@ ubuntu-dev-tools (0.131) UNRELEASED; urgency=low
     - Use wget-style progress bar (fixed width) (LP: #845787)
   * Bump python-debian B-D and Depends to 0.1.20 for unicode Changelog
     reading.
+  * backportpackage: Use absolute path of workdir when test-building.
 
   [ Colin Watson ]
   * syncpackage: Fix typo.