[gentoo-devhelp] package.env files error: unexpected EOF while looking for matching `}'

[Nikos Chantziaras]

package.env really hates me.  It seems I can do nothing useful with it. 
  I'm trying to remove a compiler flag:

   CFLAGS=${CFLAGS//-flto/}
   CXXFLAGS=${CXXFLAGS//-flto/}
   LDFLAGS=${LDFLAGS//-flto/}

However:

"/etc/portage/env/no-lto.conf", line 2: unexpected EOF while looking for 
matching `}'
"/etc/portage/env/no-lto.conf", line 3: unexpected EOF while looking for 
matching `}'
"/etc/portage/env/no-lto.conf", line 4: unexpected EOF while looking for 
matching `}'
  /"/etc/portage/env/no-lto.conf", line 2: unexpected EOF while looking 
for matching `}'
"/etc/portage/env/no-lto.conf", line 3: unexpected EOF while looking for 
matching `}'
"/etc/portage/env/no-lto.conf", line 4: unexpected EOF while looking for 
matching `}'

The string replacement syntax looks correct to me.  What am I doing wrong?