I'm experiencing that bug as well. Using symbolic links for that purpose doesn't work either.

My phone currently runs utopic r38.

This is the output I get when I run mediascanner-service ~/Music with a symbolic link set up in ~/Music pointing to ~/testmusic where I've put some music files (in subdirectories):

mediascanner-service[3032]: WARNING warning/main: No GStreamer support found for MPEG-TS (video/mpegts)
mediascanner-service[3032]: WARNING warning/main: No GStreamer support found for A/52, AC3 (Dolby Digital) Audio (audio/x-ac3; audio/ac3)
mediascanner-service[3032]: WARNING warning/main: No GStreamer support found for DTS Audio (audio/x-dts)
mediascanner-service[3032]: WARNING warning/main: No GStreamer support found for H.262/MPEG-2 Part 2 Video (video/mpeg, mpegversion=(int)2)
mediascanner-service[3032]: WARNING warning/main: No GStreamer support found for VC-1 (Windows Media) Video (video/x-wmv)
mediascanner-service[3032]: INFO info/fs-scanner: Starting to monitor "/home/phablet/Music" mounted at "/"
mediascanner-service[3032]: INFO info/main: Starting the file system scanner
mediascanner-service[3032]: INFO info/fs-walker: Scanning "/home/phablet/Music" using media index at ""/home/phablet/.cache/mediascanner""
mediascanner-service[3032]: INFO info/index: Opening media index index at ""/home/phablet/.cache/mediascanner"".
mediascanner-service[3032]: INFO info/index: Opening child index for ""/home/phablet/Downloads"" at ""/home/phablet/.cache/mediascanner""
mediascanner-service[3032]: INFO info/fs-walker: Scanning directory "/home/phablet/Music"
mediascanner-service[3032]: INFO info/fs-walker: Scanning directory "/home/phablet/Music/Black Ice (2008)"
mediascanner-service[3032]: INFO info/index: Opening child index for ""/home/phablet/Music"" at ""/home/phablet/.cache/mediascanner""
mediascanner-service[3032]: INFO info/index: Opening child index for ""/home/phablet/Pictures"" at ""/home/phablet/.cache/mediascanner""
mediascanner-service[3032]: WARNING warning/index: Ignoring media root "/home/phablet/Pictures" since no index could be created (Cannot open index writer: Read past EOF).
mediascanner-service[3032]: INFO info/index: Opening child index for ""/home/phablet/Videos"" at ""/home/phablet/.cache/mediascanner""
mediascanner-service[3032]: INFO info/index: Opening child index for ""/home/phablet/Music"" at ""/home/phablet/.cache/mediascanner""
mediascanner-service[3032]: INFO info/dbus: Published to D-Bus connection at <unix:path=/tmp/dbus-zMeBMEOH8I,type=3>
mediascanner-service[3032]: INFO info/dbus: D-Bus name lost
mediascanner-service[3032]: INFO info/fs-walker: Scanning directory "/home/phablet/Music/Ozzy Osbourne"
mediascanner-service[3032]: INFO info/fs-walker: Scanning directory "/home/phablet/Music/Ozzy Osbourne/Blizzard Of Ozz"
mediascanner-service[3032]: INFO info/fs-walker: Scanning directory "/home/phablet/Music/SLASH Featuring Myles Kennedy and The Conspirators"
mediascanner-service[3032]: INFO info/fs-walker: Scanning directory "/home/phablet/Music/SLASH Featuring Myles Kennedy and The Conspirators/Apocalyptic Love"
mediascanner-service[3032]: INFO info/fs-walker: Scanning directory "/home/phablet/Music/Guns N' Roses, Greatest Hits"
mediascanner-service[3032]: INFO info/fs-walker: Finished scanning directories below "/home/phablet/Music".
mediascanner-service[3032]: INFO info/metadata: Waiting for pending metadata resolvers.
mediascanner-service[3032]: INFO info/metadata: Metadata resolving finished.
mediascanner-service[3032]: INFO info/mediaartdownloader: Waiting for pending album art downloads.
mediascanner-service[3032]: INFO info/mediaartdownloader: Album art downloads complete.

Rebooting did not help.

Remember, this is for symbolic links. ;)