Following an upgrade to Magento Downloader 1.9.2 I found that the Magento Connect (Downloader) “check for upgrades” returned nothing (quickly) and the mage upgrade community [package name] gave the following error:
Error:
upgrade: Package community/[package name] failed: Unknown cipher in list: TLSv1
This is caused by the OpenSSL library being out of date, so either update it, or comment out line 377 in downloader/lib/Mage/HTTP/Client/Curl.php like so:
//$this->curlOption(CURLOPT_SSL_CIPHER_LIST, ‘TLSv1’)

Adendum: for 1.9.3.2 and 1.9.3.3 the fix is different:

in /downloader/lib/Mage/HTTP/Client/Curl.php line 371

change:
protected function makeRequest($method, $uri, $params = array(), $isAuthorizationRequired = false, $https = true)

to:
protected function makeRequest($method, $uri, $params = array(), $isAuthorizationRequired = false, $https = false)

(Changing the connection method to HTTP in Magento Connect Manager does NOT work.)
If the downloader is itself updated, this “fix” will need to be repeated.