src/Composer/Package/Package.php
public function replaceVersion($version, $prettyVersion)
    {
        $this->version = $version;
        $this->prettyVersion = $prettyVersion;

        $this->stability = VersionParser::parseStability($version);
        $this->dev = $this->stability === 'dev';
    }
public function replaceVersion($version, $prettyVersion)
    {
        $this->version = $version;
        $this->prettyVersion = $prettyVersion;

        $this->stability = VersionParser::parseStability($version);
        $this->dev = $this->stability === 'dev';
    }
Replaces current version and pretty version with passed values.
It also sets stability.

@param string $version       The package's normalized version
@param string $prettyVersion The package's non-normalized version