bookmarks: add incoming() to replace diff() for incoming bookmarks
This replacement makes enhancement of "show incoming bookmarks" easy,
because "compare()" can detect more detailed difference of bookmarks
between two repositories.
fixbundle() {
grep -v 'saving bundle' | grep -v 'saved backup' | \
grep -v added | grep -v adding | \
grep -v "unable to find 'e' for patching" | \
grep -v "e: No such file or directory"
}