Upgrade Prometheus to master (#2703)

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>

CHANGELOG.md

@@ -19,7 +19,7 @@ We use *breaking* word for marking changes that are not backward compatible (rel
 
 ### Changed
 
-- [#2658](https://github.com/thanos-io/thanos/pull/2658) Upgrade to Prometheus [@f4dd45609a05](https://github.com/prometheus/prometheus/commit/f4dd45609a05) which is after v2.18.1.
+- [#2658](https://github.com/thanos-io/thanos/pull/2658) [#2703](https://github.com/thanos-io/thanos/pull/2703) Upgrade to Prometheus [@3268eac2ddda](https://github.com/prometheus/prometheus/commit/3268eac2ddda) which is after v2.18.1.
     - TSDB now does memory-mapping of Head chunks and reduces memory usage.
 - [#2667](https://github.com/thanos-io/thanos/pull/2667) Store: removed support to the legacy `index.cache.json`. The hidden flag `--store.disable-index-header` was removed.
 - [#2667](https://github.com/thanos-io/thanos/pull/2667) Compact: the deprecated flag `--index.generate-missing-cache-file` and the metric `thanos_compact_generated_index_total` were removed.

go.mod

@@ -45,7 +45,7 @@ require (
 	github.com/prometheus/client_golang v1.6.0
 	github.com/prometheus/client_model v0.2.0
 	github.com/prometheus/common v0.10.0
-	github.com/prometheus/prometheus v1.8.2-0.20200522113006-f4dd45609a05
+	github.com/prometheus/prometheus v1.8.2-0.20200601152113-3268eac2ddda
 	github.com/sercand/kuberesolver v2.4.0+incompatible // indirect
 	github.com/uber/jaeger-client-go v2.23.0+incompatible
 	github.com/uber/jaeger-lib v2.2.0+incompatible
@@ -72,7 +72,7 @@ replace (
 	// Mitigation for: https://github.com/Azure/go-autorest/issues/414
 	github.com/Azure/go-autorest => github.com/Azure/go-autorest v12.3.0+incompatible
 	// Make sure Cortex is not forcing us to some other Prometheus version.
-	github.com/prometheus/prometheus => github.com/prometheus/prometheus v1.8.2-0.20200522113006-f4dd45609a05 // @f4dd45609a05e8f582cdcd8ef369004d1f9e3c02 (current master after v2.18.0).
+	github.com/prometheus/prometheus => github.com/prometheus/prometheus v1.8.2-0.20200601152113-3268eac2ddda // Master after v2.18.0 including m-map fixes.
 	k8s.io/api => k8s.io/api v0.17.5
 	k8s.io/apimachinery => k8s.io/apimachinery v0.17.5
 	k8s.io/client-go => k8s.io/client-go v0.17.5

go.sum

@@ -861,8 +861,8 @@ github.com/prometheus/procfs v0.0.8 h1:+fpWZdT24pJBiqJdAwYBjPSk+5YmQzYNPYzQsdzLk
 github.com/prometheus/procfs v0.0.8/go.mod h1:7Qr8sr6344vo1JqZ6HhLceV9o3AJ1Ff+GxbHq6oeK9A=
 github.com/prometheus/procfs v0.0.11 h1:DhHlBtkHWPYi8O2y31JkK0TF+DGM+51OopZjH/Ia5qI=
 github.com/prometheus/procfs v0.0.11/go.mod h1:lV6e/gmhEcM9IjHGsFOCxxuZ+z1YqCvr4OA4YeYWdaU=
-github.com/prometheus/prometheus v1.8.2-0.20200522113006-f4dd45609a05 h1:Tzn/Jcv/ORgKB59kGKNb95ThgrwuPBTgbdp09V+wM/Q=
-github.com/prometheus/prometheus v1.8.2-0.20200522113006-f4dd45609a05/go.mod h1:QKHYbx8sTY1fj75M+lL+LhzDSFM00+dOBlFn5wBi+14=
+github.com/prometheus/prometheus v1.8.2-0.20200601152113-3268eac2ddda h1:Jui4sQi6B+H2hI9aLPgZSjIu1dWhfJXfvVGT+gjhMhA=
+github.com/prometheus/prometheus v1.8.2-0.20200601152113-3268eac2ddda/go.mod h1:QKHYbx8sTY1fj75M+lL+LhzDSFM00+dOBlFn5wBi+14=
 github.com/rafaeljusto/redigomock v0.0.0-20190202135759-257e089e14a1/go.mod h1:JaY6n2sDr+z2WTsXkOmNRUfDy6FN0L6Nk7x06ndm4tY=
 github.com/rcrowley/go-metrics v0.0.0-20181016184325-3113b8401b8a/go.mod h1:bCqnVzQkZxMG4s8nGwiZ5l3QUCyqpo9Y+/ZMZ9VjZe4=
 github.com/retailnext/hllpp v1.0.1-0.20180308014038-101a6d2f8b52/go.mod h1:RDpi1RftBQPUCDRw6SmxeaREsAaRKnOclghuzp/WRzc=