Respect root .gitignore while globbing. (#1209)

Instead of globbing everything for **/spago.yaml and then filtering the
matches against .gitignore files, use every entry in the root .gitignore as
a negative match (ignore) while globbing.

The resulting matches still need to be checked seperately using
`Git.isIgnored`, because the new function only considers the root
.gitignore file, .gitignore files in subdirectories are ignored.

src/Spago/Config.purs

@@ -163,6 +163,31 @@ type ReadWorkspaceOptions =
   , migrateConfig :: Boolean
   }
 
+-- | Same as `Glob.match'` but if there is a .gitignore file in the same directory,
+-- | then the `ignore` option will be filled accordingly.
+-- | This function does not respect any .gitignore files in subdirectories.
+-- | Translation of: https://github.com/sindresorhus/globby/issues/50#issuecomment-467897064
+gitIgnoringGlob :: String -> Array String -> Spago (LogEnv _) { failed :: Array String, succeeded :: Array String }
+gitIgnoringGlob dir patterns = do
+  gitignore <- try (liftAff $ FS.readTextFile $ Path.concat [ dir, ".gitignore" ]) >>= case _ of
+    Left err -> do
+      logDebug $ "Could not read .gitignore to exclude directories from globbing, error: " <> Aff.message err
+      pure ""
+    Right contents -> pure contents
+  let
+    isComment = isJust <<< String.stripPrefix (String.Pattern "#")
+    dropPrefixSlashes line = maybe line dropPrefixSlashes $ String.stripPrefix (String.Pattern "/") line
+    dropSuffixSlashes line = maybe line dropSuffixSlashes $ String.stripSuffix (String.Pattern "/") line
+
+    ignore :: Array String
+    ignore =
+      map (dropSuffixSlashes <<< dropPrefixSlashes)
+        $ Array.filter (not <<< or [ String.null, isComment ])
+        $ map String.trim
+        $ String.split (String.Pattern "\n")
+        $ gitignore
+  liftAff $ Glob.match' dir patterns { ignore: [ ".spago" ] <> ignore }
+
 -- | Reads all the configurations in the tree and builds up the Map of local
 -- | packages to be integrated in the package set
 readWorkspace :: ReadWorkspaceOptions -> Spago (Registry.RegistryEnv _) Workspace
@@ -198,7 +223,7 @@ readWorkspace { maybeSelectedPackage, pureBuild, migrateConfig } = do
 
   logDebug "Gathering all the spago configs in the tree..."
   { succeeded: otherConfigPaths, failed, ignored } <- do
-    result <- liftAff $ Glob.match' Paths.cwd [ "**/spago.yaml" ] { ignore: [ ".spago", "spago.yaml" ] }
+    result <- gitIgnoringGlob Paths.cwd [ "**/spago.yaml" ]
     -- If a file is gitignored then we don't include it as a package
     let
       filterGitignored path = do