diff --git a/scripts/build.py b/scripts/build.py
index 265bbc06..9a5b8950 100644
--- a/scripts/build.py
+++ b/scripts/build.py
@@ -20,77 +20,78 @@ glob_order = []
 proj_base=pwd.getpwuid(os.getuid()).pw_dir + "/local/src/cvs.stable/proj"
 search_path=[".", "dspc/src", "dspc/src/dspcd-plugins", "dspc/src/io" ]
 glob_prereq_type="BUILD"
+dep_cache = {}
 
 def find_proj_path(name):
-	name=name.replace("dspider-", "")
-	for sub in search_path:
-		path=proj_base + "/" + sub + "/" + name
-		if os.path.exists(path):
-			return path
-	raise Exception("module " + name + " not found below " + proj_base)
+    name=name.replace("dspider-", "")
+    for sub in search_path:
+        path=proj_base + "/" + sub + "/" + name
+        if os.path.exists(path):
+            return path
+    raise Exception("module " + name + " not found below " + proj_base)
 
 def read_deps(cur, prereq_type):
-	path = find_proj_path(cur)
-	os.chdir(path)
+    path = find_proj_path(cur)
+    os.chdir(path)
         # ignoring prereq_type, as it has never been anything but BUILD, now
         # only looking for PREREQ without anything
-	p = subprocess.Popen("LD_LIBRARY_PATH= make echo-prereq | sed '/PREREQ " + " *=/ !d; s/.*=//'", shell=True, stdout=subprocess.PIPE)
-	p.wait()
-	if p.returncode: # FIXME: doesn't work, because sed kills make's return code
-		raise Exception("failed to get " + prereq_type + " prerequisites from " + path)
-	r = Set()
-	for d in p.stdout.read().split():
-		r.add(d)
-	if cur in r:
-		r.remove(cur)
-	return r
+    p = subprocess.Popen("LD_LIBRARY_PATH= make echo-prereq | sed '/PREREQ " + " *=/ !d; s/.*=//'", shell=True, stdout=subprocess.PIPE)
+    p.wait()
+    if p.returncode: # FIXME: doesn't work, because sed kills make's return code
+        raise Exception("failed to get " + prereq_type + " prerequisites from " + path)
+    r = Set()
+    for d in p.stdout.read().split():
+        r.add(d)
+    if cur in r:
+        r.remove(cur)
+    return r
 
 def add_tree(cur, prereq_type):
-	if cur in all_deps:
-		return 0
-	all_deps.add(cur)
-	deps = read_deps(cur, prereq_type)
-	for d in deps:
-		add_tree(d, prereq_type)
-	dep_tree[cur] = deps
-	return len(deps)
+    if cur in all_deps:
+        return 0
+    all_deps.add(cur)
+    deps = read_deps(cur, prereq_type)
+    for d in deps:
+        add_tree(d, prereq_type)
+    dep_tree[cur] = deps
+    return len(deps)
 
 def calculate_order(order, modules, prereq_type):
-	for m in modules:
-		add_tree(m, prereq_type)
-	while len(all_deps):
-		for d in all_deps:
-			if not len(dep_tree[d]):
-				break
-		else:
-			print all_deps
-			raise Exception("fatal: the dependencies between these modules are unresolvable")
-		order.append(d)
-		all_deps.remove(d)
-		for k in dep_tree.keys():
-			if d in dep_tree[k]:
-				dep_tree[k].remove(d)
-	return 1
+    for m in modules:
+        add_tree(m, prereq_type)
+    while len(all_deps):
+        for d in all_deps:
+            if not len(dep_tree[d]):
+                break
+        else:
+            print all_deps
+            raise Exception("fatal: the dependencies between these modules are unresolvable")
+        order.append(d)
+        all_deps.remove(d)
+        for k in dep_tree.keys():
+            if d in dep_tree[k]:
+                dep_tree[k].remove(d)
+    return 1
 
 def run_make(module, target):
-	path = find_proj_path(module)
-	print "========= running make " + target + " in " + path
-	os.chdir(path)
-	if subprocess.call(["make", target]):
-		raise Exception(time.strftime("%Y-%m-%d %H:%M") + ": failed to make target " + target + " in module " + module + " below base " + proj_base)
+    path = find_proj_path(module)
+    print "========= running make " + target + " in " + path
+    os.chdir(path)
+    if subprocess.call(["make", target]):
+        raise Exception(time.strftime("%Y-%m-%d %H:%M") + ": failed to make target " + target + " in module " + module + " below base " + proj_base)
 
 def build(modules, order, target):
-	if target in ["clean", "distclean"]:
-		for m in reversed(order):
-			run_make(m, target)
-			if m in modules:
-				modules.remove(m)
-			if not len(modules):
-				print "all modules cleaned"
-				return
-	else:
-		for m in order:
-			run_make(m, target)
+    if target in ["clean", "distclean"]:
+        for m in reversed(order):
+            run_make(m, target)
+            if m in modules:
+                modules.remove(m)
+            if not len(modules):
+                print "all modules cleaned"
+                return
+    else:
+        for m in order:
+            run_make(m, target)
 
 # -- parse command line
 modules = Set()
@@ -109,8 +110,8 @@ modules=args.modules
 
 env_exclude=os.getenv('BUILD_EXCLUDE', '')
 if len(env_exclude):
-	print "exluding modules from environment: " + env_exclude
-	exclude += " " + env_exclude
+    print "exluding modules from environment: " + env_exclude
+    exclude += " " + env_exclude
 
 # -- build
 if target != 'order':