guix: import: Fix parsing Cabal files that import many stanzas

* guix/import/cabal.scm (eval-cabal)[eval]: Split imports to a
normalized list before mapping over it.
* tests/hackage.scm: Test it.

Change-Id: I39ece019251b6a23a937c8562d2d4a545a6bc7df
Signed-off-by: Lars-Dominik Braun <lars@6xq.net>

tests/hackage.scm

@@ -622,4 +622,49 @@ executable cabal
 (test-assert "hackage->guix-package test cabal import"
   (eval-test-with-cabal test-cabal-import match-ghc-foo-import))
 
+(define test-cabal-multiple-imports
+  "name: foo
+version: 1.0.0
+homepage: http://test.org
+synopsis: synopsis
+description: description
+license: BSD3
+common commons
+  build-depends:
+    HTTP       >= 4000.2.5 && < 4000.3,
+    mtl        >= 2.0      && < 3
+
+common others
+  build-depends:
+    base == 4.16.*,
+    stm-chans == 3.0.*
+
+executable cabal
+  import:
+      commons
+    , others
+")
+
+(define-package-matcher match-ghc-foo-multiple-imports
+  ('package
+    ('name "ghc-foo")
+    ('version "1.0.0")
+    ('source
+     ('origin
+       ('method 'url-fetch)
+       ('uri ('hackage-uri "foo" 'version))
+       ('sha256
+        ('base32
+         (? string? hash)))))
+    ('build-system 'haskell-build-system)
+    ('properties '(quote ((upstream-name . "foo"))))
+    ('inputs ('list 'ghc-http 'ghc-stm-chans))
+    ('home-page "http://test.org")
+    ('synopsis (? string?))
+    ('description (? string?))
+    ('license 'license:bsd-3)))
+
+(test-assert "hackage->guix-package test cabal multiple imports"
+  (eval-test-with-cabal test-cabal-multiple-imports match-ghc-foo-multiple-imports))
+
 (test-end "hackage")