make sure not to use cached channels for nix-channel --update

fixes #1964

3 files changed, 4 insertions, 4 deletions

diff --git a/src/libstore/download.cc b/src/libstore/download.cc
index 18f9094f82e0..54f4dd218007 100644
--- a/src/libstore/download.cc
+++ b/src/libstore/download.cc
@@ -623,7 +623,7 @@ DownloadResult Downloader::download(const DownloadRequest & request)
     return enqueueDownload(request).get();
 }
 
-Path Downloader::downloadCached(ref<Store> store, const string & url_, bool unpack, string name, const Hash & expectedHash, string * effectiveUrl)
+Path Downloader::downloadCached(ref<Store> store, const string & url_, bool unpack, string name, const Hash & expectedHash, string * effectiveUrl, int ttl)
 {
     auto url = resolveUri(url_);
 
@@ -653,7 +653,6 @@ Path Downloader::downloadCached(ref<Store> store, const string & url_, bool unpa
 
     string expectedETag;
 
-    int ttl = settings.tarballTtl;
     bool skip = false;
 
     if (pathExists(fileLink) && pathExists(dataFile)) {
diff --git a/src/libstore/download.hh b/src/libstore/download.hh
index 0b8d29b21dfe..7ade756fc356 100644
--- a/src/libstore/download.hh
+++ b/src/libstore/download.hh
@@ -2,6 +2,7 @@
 
 #include "types.hh"
 #include "hash.hh"
+#include "globals.hh"
 
 #include <string>
 #include <future>
@@ -54,7 +55,7 @@ struct Downloader
        use the recorded ETag to verify if the server has a more
        recent version, and if so, download it to the Nix store. */
     Path downloadCached(ref<Store> store, const string & uri, bool unpack, string name = "",
-        const Hash & expectedHash = Hash(), string * effectiveUri = nullptr);
+        const Hash & expectedHash = Hash(), string * effectiveUri = nullptr, int ttl = settings.tarballTtl);
 
     enum Error { NotFound, Forbidden, Misc, Transient, Interrupted };
 };
diff --git a/src/nix-channel/nix-channel.cc b/src/nix-channel/nix-channel.cc
index d1b47ede803f..55ebda438965 100755
--- a/src/nix-channel/nix-channel.cc
+++ b/src/nix-channel/nix-channel.cc
@@ -86,7 +86,7 @@ static void update(const StringSet & channelNames)
         // definition from a consistent location if the redirect changes mid-download.
         std::string effectiveUrl;
         auto dl = getDownloader();
-        auto filename = dl->downloadCached(store, url, false, "", Hash(), &effectiveUrl);
+        auto filename = dl->downloadCached(store, url, false, "", Hash(), &effectiveUrl, 0);
         url = chomp(std::move(effectiveUrl));
 
         // If the URL contains a version number, append it to the name