Test for indicentally-fixed #5195.

I fixed this in passing with #5284, but let's add a test to make sure
it stays fixed. The error message isn't perfect, but it's a lot better
than failing silently!

Closes #5195.

cabal-testsuite/PackageTests/SDist/T5195/Main.hs

@@ -0,0 +1 @@
+main = putStrLn "hi"

cabal-testsuite/PackageTests/SDist/T5195/cabal.out

@@ -0,0 +1,2 @@
+# cabal sdist
+cabal: filepath wildcard './actually-a-directory' does not match any files.

cabal-testsuite/PackageTests/SDist/T5195/cabal.test.hs

@@ -0,0 +1,6 @@
+import Test.Cabal.Prelude
+main = cabalTest $ do
+  tmpdir <- fmap testTmpDir getTestEnv
+  let fn = tmpdir </> "sources"
+  res <- fails $ cabal' "sdist" ["--list-sources=" ++ fn]
+  assertOutputContains "filepath wildcard './actually-a-directory' does not match any files" res

cabal-testsuite/PackageTests/SDist/T5195/t5195.cabal

@@ -0,0 +1,10 @@
+cabal-version: 2.2
+name: t5195
+version: 0
+
+extra-source-files:
+  ./actually-a-directory
+
+executable foo
+  default-language: Haskell2010
+  main-is: Main.hs