S3BinaryCacheStore:: Eliminate a string copy while uploading

This cuts hydra-queue-runner's peak memory usage by about a third.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libutil/hash.cc b/src/libutil/hash.cc
index 81aced0fde16..49e781980f3a 100644
--- a/src/libutil/hash.cc
+++ b/src/libutil/hash.cc
@@ -106,7 +106,7 @@ Hash parseHash(HashType ht, const string & s)
         string s2(s, i * 2, 2);
         if (!isxdigit(s2[0]) || !isxdigit(s2[1]))
             throw BadHash(format("invalid hash ‘%1%’") % s);
-        std::istringstream str(s2);
+        istringstream_nocopy str(s2);
         int n;
         str >> std::hex >> n;
         hash.hash[i] = n;