package_hash: add code to generate a hash for a package file

This will be included in the full hash of packages.

var/spack/repos/builtin.mock/packages/hash-test1/package.py

@@ -0,0 +1,34 @@
+from spack import *
+
+import os
+
+
+class HashTest1(Package):
+    """Used to test package hashing
+    """
+
+    homepage = "http://www.hashtest1.org"
+    url = "http://www.hashtest1.org/downloads/hashtest1-1.1.tar.bz2"
+
+    version('1.1', 'a' * 32)
+    version('1.2', 'b' * 32)
+    version('1.3', 'c' * 32)
+    version('1.4', 'd' * 32)
+
+    patch('patch1.patch', when="@1.1")
+    patch('patch2.patch', when="@1.4")
+
+    variant('variantx', default=False, description='Test variant X')
+    variant('varianty', default=False, description='Test variant Y')
+
+    def setup_dependent_environment(self, spack_env, run_env, dependent_spec):
+        pass
+
+    @when('@:1.4')
+    def install(self, spec, prefix):
+        print("install 1")
+        os.listdir(os.getcwd())
+
+    @when('@1.5')
+    def install(self, spec, prefix):
+        os.listdir(os.getcwd())

var/spack/repos/builtin.mock/packages/hash-test1/patch1.patch

@@ -0,0 +1 @@
+the contents of patch 1 (not a valid diff, but sufficient for testing)

var/spack/repos/builtin.mock/packages/hash-test1/patch2.patch

@@ -0,0 +1 @@
+the contents of patch 2 (not a valid diff, but sufficient for testing)

var/spack/repos/builtin.mock/packages/hash-test2/package.py

@@ -0,0 +1,28 @@
+from spack import *
+
+import os
+
+
+class HashTest2(Package):
+    """Used to test package hashing
+    """
+
+    homepage = "http://www.hashtest2.org"
+    url = "http://www.hashtest1.org/downloads/hashtest2-1.1.tar.bz2"
+
+    version('1.1', 'a' * 32)
+    version('1.2', 'b' * 32)
+    version('1.3', 'c' * 31 + 'x')  # Source hash differs from hash-test1@1.3
+    version('1.4', 'd' * 32)
+
+    patch('patch1.patch', when="@1.1")
+
+    variant('variantx', default=False, description='Test variant X')
+    variant('varianty', default=False, description='Test variant Y')
+
+    def setup_dependent_environment(self, spack_env, run_env, dependent_spec):
+        pass
+
+    def install(self, spec, prefix):
+        print("install 1")
+        os.listdir(os.getcwd())

var/spack/repos/builtin.mock/packages/hash-test2/patch1.patch

@@ -0,0 +1,2 @@
+the different contents of patch 1 (not a valid diff, but sufficient for testing,
+and different from patch 1 of hash-test1)