gnu: python2-larch: Enable tests.

* gnu/packages/patches/python2-larch-coverage-4.0a6-compatibility.patch: New
file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/python.scm (python2-larch)[source]: Use it.
[arguments]: Move 'check' phase to before 'build' phase.

gnu/packages/patches/python2-larch-coverage-4.0a6-compatibility.patch

@@ -0,0 +1,29 @@
+From ca548da9ba78ddee90779051210e3e89185e4f7d Mon Sep 17 00:00:00 2001
+From: Michel Alexandre Salim <michel@michel-slm.name>
+Date: Mon, 15 Feb 2016 23:03:42 +0700
+Subject: coverage-4.0a6 compatibility
+
+coverage 4.0a6 no longer generates .coverage file, so use -f when
+deleting .coverage to ensure deletion does not fail.
+---
+ Makefile | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+(limited to 'Makefile')
+
+diff --git a/Makefile b/Makefile
+index 7818f57..362c07f 100644
+--- a/Makefile
++++ b/Makefile
+@@ -23,7 +23,7 @@ fsck-larch.1: fsck-larch.1.in fsck-larch
+ 
+ check:
+ 	python -m CoverageTestRunner --ignore-missing-from=without-tests
+-	rm .coverage
++	rm -f .coverage
+ 	./insert-remove-test tempdir 100
+ 	rm -r tempdir larch.log
+ 	cmdtest tests
+-- 
+cgit v1.1
+