Adds integration test for commercialhaskell#3396

The provided test package (dinamo), that is part of a custom snapshot has
a malformed cabal file. Specifically, it's setting the required cabal
version to an invalid number (9001). This test makes sure that
stack does not care about this if we do not actually use the package
in our project.

test/integration/tests/3396-package-indices/Main.hs

@@ -0,0 +1,11 @@
+import           StackTest
+import           System.Directory   (createDirectory)
+import           System.Environment (getEnv)
+import           System.FilePath    ((</>))
+
+main :: IO ()
+main = do
+  home <- getEnv "HOME"
+  createDirectory (home </> ".stack" </> "indices" </> "CustomIndex")
+  copy "CustomIndex/01-index.tar" (home </> ".stack"  </> "indices" </> "CustomIndex" </> "01-index.tar")
+  stack ["build"]

test/integration/tests/3396-package-indices/files/files.cabal

@@ -0,0 +1,19 @@
+name:                files
+version:             0.1.0.0
+-- synopsis:
+-- description:
+homepage:            https://github.com/githubuser/files#readme
+license:             BSD3
+author:              Author name here
+maintainer:          example@example.com
+copyright:           2017 Author name here
+category:            Web
+build-type:          Simple
+cabal-version:       >=1.10
+
+library
+  hs-source-dirs:      src
+  exposed-modules:     Lib
+  build-depends:       base >= 4.7 && < 5
+  default-language:    Haskell2010
+

test/integration/tests/3396-package-indices/files/my-snapshot.yaml

@@ -0,0 +1,11 @@
+compiler: ghc-8.0.2
+name: my-snapshot
+
+packages:
+  - base-4.10.0.0
+  - dinamo-0.1.0.0
+
+flags:
+  dinamo:
+    debug: true
+

test/integration/tests/3396-package-indices/files/src/Lib.hs

@@ -0,0 +1,8 @@
+module Lib
+    ( someFunc
+    ) where
+
+
+someFunc :: IO ()
+someFunc = print "some func"
+

test/integration/tests/3396-package-indices/files/stack.yaml

@@ -0,0 +1,18 @@
+resolver: my-snapshot.yaml
+
+packages:
+- .
+
+extra-deps: []
+
+# Override default flag values for local packages and extra-deps
+flags: {}
+
+# Extra package databases containing global packages
+extra-package-dbs: []
+
+package-indices:
+  - name: CustomIndex
+    download-prefix: http://0.0.0.0:8080/
+    http: http://0.0.0.0:8080/custom.index.tar.gz
+