Epiphany version 1.4.0 contains this in configure.in:

dnl Split up the version string ( 1.7rc1 -> 1 7 rc 1 )
version=$(echo $MOZILLA_VERSION | sed -e 's/\(@<:@0-9@:>@\+\|@<:@a-z@:>@\+\)/\1
/g' -e 's/\.//g')

This doesn't work with solaris sed.
SunOS birkhoff 5.9 Generic_117171-07 sun4u sparc SUNW,Ultra-Enterprise

I was able to just use s/\./ /g because my mozilla version was not a prerelease.
 This will obviously not work in the general case.