More error message improvements

git-svn-id: http://svn.savannah.nongnu.org/svn/rdiff-backup@976 2b77aa54-bcbc-44c9-a7ec-4f6cf2b41109

trunk/rdiff-backup/rdiff_backup/Main.py

@@ -444,7 +444,7 @@ option.""" % rpout.path)
 	if not Globals.rbdir.lstat():
 		try:
 			Globals.rbdir.mkdir()
-		except IOError, exc:
+		except (OSError, IOError), exc:
 			Log.FatalError(
 """Could not create rdiff-backup directory
 

trunk/rdiff-backup/rdiff_backup/backup.py

@@ -707,7 +707,9 @@ class IncrementITRB(PatchITRB):
 		self.base_rp, inc_prefix = longname.get_mirror_inc_rps(
 			self.CCPP.get_rorps(index), self.basis_root_rp, self.inc_root_rp)
 		self.base_rp.setdata()
-		assert diff_rorp.isdir() or self.base_rp.isdir()
+		assert diff_rorp.isdir() or self.base_rp.isdir(), \
+				("Either %s or %s must be a directory" % (repr(diff_rorp.path),
+				 repr(self.base_rp.path)))
 		if diff_rorp.isdir():
 			inc = increment.Increment(diff_rorp, self.base_rp, inc_prefix)
 			if inc and inc.isreg():