Install mdbook from source

Works around a numbering bug!

Closes rustwasm/book#158

Author: alexcrichton

Diff for: azure-pipelines.yml

@@ -4,11 +4,6 @@ trigger:
 jobs:
   - job: publish
     steps:
-      - script: |
-          set -e
-          curl -L https://github.com/rust-lang-nursery/mdBook/releases/download/v0.2.1/mdbook-v0.2.1-x86_64-unknown-linux-musl.tar.gz | tar xzf -
-          echo "##vso[task.prependpath]$PWD"
-        displayName: Install mdbook
       - task: UseRubyVersion@0
         inputs:
           versionSpec: '>= 2.4'
@@ -21,6 +16,14 @@ jobs:
           curl https://sh.rustup.rs -sSf | sh -s -- -y
           echo "##vso[task.prependpath]$HOME/.cargo/bin"
         displayName: Install rust
+      # Temporarily disable using pre-built binaries until
+      # https://github.com/rust-lang-nursery/mdBook/issues/820 is fixed.
+      # - script: |
+      #     set -e
+      #     curl -L https://github.com/rust-lang-nursery/mdBook/releases/download/v0.2.1/mdbook-v0.2.1-x86_64-unknown-linux-musl.tar.gz | tar xzf -
+      #     echo "##vso[task.prependpath]$PWD"
+      - script: cargo install mdbook --version 0.2.3
+        displayName: Install mdbook
       - script: ./ci/build.sh
         displayName: Build site
       - script: |