ubiquity fails to build from source in wily. In fact, you cannot even build the source package because that runs ./tests/run-pep8 which fails with the following errors.
./tests/run-pep8
bin/ubiquity:35:1: E402 module level import not at top of file
bin/ubiquity-wrapper:13:1: E402 module level import not at top of file
bin/ubiquity-dm:23:1: E402 module level import not at top of file
bin/ubiquity-dm:24:1: E402 module level import not at top of file
bin/ubiquity-dm:25:1: E402 module level import not at top of file
bin/ubiquity-dm:26:1: E402 module level import not at top of file
bin/ubiquity-dm:27:1: E402 module level import not at top of file
bin/ubiquity-dm:294:45: W503 line break before binary operator
scripts/install.py:39:1: E402 module level import not at top of file
scripts/plugininstall.py:46:1: E402 module level import not at top of file
scripts/plugininstall.py:47:1: E402 module level import not at top of file
ubiquity/plugin_manager.py:30:16: W503 line break before binary operator
ubiquity/frontend/gtk_ui.py:55:1: E402 module level import not at top of file
ubiquity/frontend/gtk_ui.py:57:1: E402 module level import not at top of file
ubiquity/frontend/gtk_ui.py:58:1: E402 module level import not at top of file
ubiquity/frontend/gtk_ui.py:59:1: E402 module level import not at top of file
ubiquity/frontend/gtk_ui.py:60:1: E402 module level import not at top of file
ubiquity/frontend/gtk_ui.py:61:1: E402 module level import not at top of file
ubiquity/frontend/kde_ui.py:42:1: E402 module level import not at top of file
ubiquity/frontend/kde_ui.py:44:1: E402 module level import not at top of file
ubiquity/frontend/kde_ui.py:45:1: E402 module level import not at top of file
ubiquity/frontend/kde_ui.py:46:1: E402 module level import not at top of file
ubiquity/frontend/kde_ui.py:47:1: E402 module level import not at top of file
ubiquity/frontend/kde_ui.py:48:1: E402 module level import not at top of file
ubiquity/frontend/kde_ui.py:49:1: E402 module level import not at top of file
ubiquity/frontend/kde_ui.py:50:1: E402 module level import not at top of file
ubiquity/frontend/kde_ui.py:51:1: E402 module level import not at top of file
ubiquity/frontend/kde_ui.py:52:1: E402 module level import not at top of file
ubiquity/frontend/kde_ui.py:190:17: W503 line break before binary operator
ubiquity/frontend/kde_ui.py:191:17: W503 line break before binary operator
ubiquity/frontend/gtk_components/nmwidgets.py:6:1: E402 module level import not at top of file
ubiquity/frontend/gtk_components/nmwidgets.py:8:1: E402 module level import not at top of file
ubiquity/frontend/kde_components/nmwidgets.py:33:1: E402 module level import not at top of file
ubiquity/frontend/kde_components/nmwidgets.py:34:1: E402 module level import not at top of file
ubiquity/frontend/kde_components/nmwidgets.py:36:1: E402 module level import not at top of file
ubiquity/frontend/kde_components/nmwidgets.py:37:1: E402 module level import not at top of file
ubiquity/frontend/kde_components/nmwidgets.py:38:1: E402 module level import not at top of file
ubiquity/plugins/ubi-partman.py:342:17: W503 line break before binary operator
ubiquity/plugins/ubi-partman.py:1452:27: W503 line break before binary operator
debian/rules:46: recipe for target 'check' failed
make: *** [check] Error 1
2.1.28 fixes this.