Bring bash quoting back.

See #110. [skip ci]

.appveyor.yml

@@ -5,14 +5,14 @@ install:
     - set PATH=C:\msys64\mingw64\bin;C:\msys64\usr\local\bin;C:\msys64\usr\bin;%PATH%
     - curl -ostack.zip -LsS --insecure https://www.stackage.org/stack/windows-x86_64
     - 7z x stack.zip stack.exe
-    - bash -lc 'curl -LsS http://www.haskell.org/ghc/dist/7.10.3/ghc-7.10.3-x86_64-unknown-mingw32.tar.xz | tar -xJ -C /mingw64 --strip-components=1'
+    - bash -lc "curl -LsS http://www.haskell.org/ghc/dist/7.10.3/ghc-7.10.3-x86_64-unknown-mingw32.tar.xz | tar -xJ -C /mingw64 --strip-components=1"
     - stack exec -- pacman -S --noconfirm gcc binutils p7zip git
     - echo "" | stack --no-terminal install alex happy shake ansi-terminal mtl
     - set PATH=%PATH%;C:\Users\appveyor\AppData\Roaming\local\bin\
     - git clone --recursive git://git.haskell.org/ghc.git C:\msys64\home\ghc\tmp
-    - bash -lc 'mv /home/ghc/tmp/* /home/ghc'
+    - bash -lc "mv /home/ghc/tmp/* /home/ghc"
 
 build_script:
-    - bash -lc 'cd /home/ghc && ./boot'
-    - bash -lc 'cd /home/ghc && echo "" | ./configure --enable-tarballs-autodownload'
-    - bash -lc 'cd /home/ghc && ./shake-build/build.bat -j --no-progress'
+    - bash -lc "cd /home/ghc && ./boot"
+    - bash -lc "cd /home/ghc && echo \"\" | ./configure --enable-tarballs-autodownload"
+    - bash -lc "cd /home/ghc && ./shake-build/build.bat -j --no-progress"