BUCK: fix build against unpublished JARs

This change fixes the following problems:

* MAVEN_LOCAL definition must be prefixed with 'file://' for curl to work
* src_sha1 was unnecessary required to define source artifact
* update the documentation that sha1 must not be provided

Change-Id: I1cee6588897c928f01bac5cc9fb252251f4f8027

Documentation/dev-buck.txt

@@ -241,8 +241,6 @@ that artifact:
  maven_jar(
    name = 'gwtorm',
    id = 'gwtorm:gwtorm:42',
-   bin_sha1 = None,
-   src_sha1 = None,
    license = 'Apache2.0',
    repository = MAVEN_LOCAL,
  )

lib/maven.defs

@@ -91,13 +91,12 @@ def maven_jar(
       deps = ['//tools:download_file'],
       out = srcjar,
     )
-    if src_sha1:
-      prebuilt_jar(
-        name = name + '_src',
-        binary_jar = genfile(srcjar),
-        deps = license + [':' + name + '__download_src'],
-        visibility = visibility,
-      )
+    prebuilt_jar(
+      name = name + '_src',
+      binary_jar = genfile(srcjar),
+      deps = license + [':' + name + '__download_src'],
+      visibility = visibility,
+    )
   else:
     srcjar = None
     genrule(

tools/download_file.py

@@ -26,7 +26,7 @@ from zipfile import ZipFile, BadZipfile, LargeZipFile
 REPO_ROOTS = {
   'GERRIT': 'http://gerrit-maven.storage.googleapis.com',
   'MAVEN_CENTRAL': 'http://repo1.maven.org/maven2',
-  'MAVEN_LOCAL': path.expanduser('~/.m2/repository'),
+  'MAVEN_LOCAL': 'file://' + path.expanduser('~/.m2/repository'),
 }
 
 GERRIT_HOME = path.expanduser('~/.gerritcodereview')