Silence "mv" and eliminate some "cd" commands
Remove .hgignore files
Trac #9939: Remove unnecessary .hgignore files

URL: http://trac.sagemath.org/9939
Reported by: mpatel
Ticket author(s): Jeroen Demeyer
Reviewer(s): Marc Mezzarobba
Trac #15766: sage-spkg can show harmless "mv" error

The `mv` command in
{{{
if [ "$USE_LOCAL_SCRIPTS" = yes ]; then
    mv "${PKG_NAME_UPSTREAM%.tar*}" src
    cd ..
    echo "Finished set up"
else
}}}
can sometimes give an error which is harmless. So we should silence this
error. We can also remove some extra `cd` commands.

URL: http://trac.sagemath.org/15766
Reported by: jdemeyer
Ticket author(s): Jeroen Demeyer
Reviewer(s): R. Andrew Ohana