I found this little bug on my server today: If a map-specific config has a forcecvar value that is not specified on the default config, after playing the map and switching to new map, clients who play with ET:Legacy are not forced to change that cvar back to default value. Here is an example that we encountered on our server today:
On our server, radar.cfg has forcecvar r_wolffog "0" and r_drawfoliage "0". We played radar, and forcecvars worked normally. Then we switched to Baserace. For me, fog was automatically forced back to 1, like the default value in ET is. But my friend who played with ET:Legacy, still had it on 0 and could toggle it. Same bug happened on et_ufo after that. But when I modified default.cfg to have forcecvar r_wolffog "1" and r_drawfoliage "1" and changed map to battery, my friend with ET:Legacy was forced to have r_wolffog "0" and couldn't change it. I was able to reproduce the entire issue just few minutes ago, with the exception that I couldn't change r_wolffog back to 1 after having forced it to 0 on radar.
My friend played on Linux with ET:L 2.71 RC3, and I tried this on Windows with ET:L 2.71 RC4. Server is running silEnT 0.8.2.