protover: Using twice the same version for old tor
`protover_compute_for_old_tor()` checks twice `0.2.7.5` version leading to dead code.
According to the comment and the spec, it should be `0.2.9.1-alpha`.
```
} else if (tor_version_as_new_as(version, "0.2.7.5")) {
/* 0.2.9.1-alpha HSRend=2 */
return "Cons=1-2 Desc=1-2 DirCache=1 HSDir=1 HSIntro=3 HSRend=1-2 "
"Link=1-4 LinkAuth=1 "
"Microdesc=1-2 Relay=1-2";
```
Patch coming up.
issue