Make `CurlDownloadStrategy` resume aborted downloads

* `CurlDownloadStrategy#_fetch` (and the same methods in its
  subclasses) now fetches the file to a temporary path, and
  `CurlDownloadStrategy#fetch` moves it to the correct location.
* `Homebrew#cleanup` cleans the temporary files `CurlDownloadStrategy`
  creates if they're left in the cache.

Closes #13953.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/Library/Homebrew/cmd/cleanup.rb b/Library/Homebrew/cmd/cleanup.rb
index 6b4e6b400..490065606 100644
--- a/Library/Homebrew/cmd/cleanup.rb
+++ b/Library/Homebrew/cmd/cleanup.rb
@@ -77,6 +77,10 @@ module Homebrew extend self
           end
         end
       end
+      if pn.basename.to_s.split('.').last == 'incomplete'
+        puts "Removing #{pn}..."
+        rm pn unless ARGV.dry_run?
+      end
     end
   end