Iceweasel fails to load lightspark plugin

[LRN]

Compiled 4b1551bbe63bd50c4800f5b66f7d6b472a10b0ba from git master
Iceweasel says:
LoadPlugin: failed to initialize shared library /usr/lib/lightspark/liblightsparkplugin.so [/usr/lib/lightspark/liblightsparkplugin.so: undefined symbol: _ZN10lightspark10Downloader7seekoffElSt12_Ios_SeekdirSt13_Ios_Openmode]
At which point iceweasel freezes and has to be put down.

[LRN (lrn1986)]

Oh, right. Iceweasel package version is 24.0-2

[Antti Ajanki (aajanki)]

Make sure that you don't have two versions of liblightspark.so installed on your system. It could cause this kind of error. At least remove lightspark packages installed by a package manager when you are using a self-compiled version.