feature #131 Add previous exception for some 'unknown errors' (Pierstoval)

This PR was merged into the 1.0-dev branch.

Discussion
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Add previous exception for some 'unknown errors'

At the moment, we don't have that many clues when people can't install Symfony and when we can't guess what is the problem with the backtrace.

This PR allows debugging easier, especially when Distill does throw an exception.

This is related to #129

Commits
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a2f6c6d Add previous exception for some 'unknown errors'

Author: javiereguiluz

src/Symfony/Installer/DownloadCommand.php

@@ -135,7 +135,7 @@ protected function download()
                     "There was an error downloading %s from symfony.com server:\n%s",
                     $this->getDownloadedApplicationType(),
                     $e->getMessage()
-                ));
+                ), null, $e);
             }
         }
 
@@ -192,7 +192,7 @@ protected function extract()
                 "To solve this issue, check the permissions of the %s directory and\n".
                 "try executing this command again:\n%s",
                 $this->getDownloadedApplicationType(), getcwd(), $this->getExecutedCommand()
-            ));
+            ), null, $e);
         }
 
         if (!$extractionSucceeded) {