Cherry pick fix uint convert bug to release 2.1

.gitignore

@@ -15,5 +15,7 @@ y.output
 profile.coverprofile
 explain_test
 cmd/explaintest/explain-test.out
+cmd/explaintest/explaintest_tidb-server
 _tools/
 *.fail.go
+tools/bin/

.travis.yml

@@ -3,7 +3,7 @@ language: go
 go_import_path: github.com/pingcap/tidb
 
 go:
-  - "1.11"
+  - "1.12"
 
 env:
     - TRAVIS_COVERAGE=0

Dockerfile

@@ -1,9 +1,15 @@
 # Builder image
-FROM golang:1.10.1-alpine as builder
+FROM golang:1.12-alpine as builder
 
 RUN apk add --no-cache \
+    wget \
     make \
-    git
+    git \
+    gcc \
+    musl-dev
+
+RUN wget -O /usr/local/bin/dumb-init https://github.com/Yelp/dumb-init/releases/download/v1.2.2/dumb-init_1.2.2_amd64 \
+ && chmod +x /usr/local/bin/dumb-init
 
 COPY . /go/src/github.com/pingcap/tidb
 
@@ -12,13 +18,13 @@ WORKDIR /go/src/github.com/pingcap/tidb/
 RUN make
 
 # Executable image
-FROM scratch
+FROM alpine
 
 COPY --from=builder /go/src/github.com/pingcap/tidb/bin/tidb-server /tidb-server
+COPY --from=builder /usr/local/bin/dumb-init /usr/local/bin/dumb-init
 
 WORKDIR /
 
 EXPOSE 4000
 
-ENTRYPOINT ["/tidb-server"]
-
+ENTRYPOINT ["/usr/local/bin/dumb-init", "/tidb-server"]