fix load_tool error messages and cover all occourences

When a tool cannot be loaded the wrong path was displayed on the error
message. sys.path was always displayed but the actual path used depends
on tooldir being passed and on the value of with_sys_path parameter.

I put the exception handling (raising the fatal) inside load_tool itself
as this is the only place where the exact path is known, without having
to recalculate it outside. To be able to use fatal there also the ctx
has to be passed from the various points.

In this way all load_tool exceptions are caught and reported, while before
an exception during configure was not caught for example, just during the
options.

waflib/Build.py

@@ -378,7 +378,7 @@ class BuildContext(Context.Context):
 				self.setup(i, tooldir)
 			return
 
-		module = Context.load_tool(tool, tooldir)
+		module = Context.load_tool(tool, tooldir, self)
 		if hasattr(module, "setup"):
 			module.setup(self)
 

waflib/Configure.py

@@ -254,8 +254,6 @@ class ConfigurationContext(Context.Context):
 			module = None
 			try:
 				module = Context.load_tool(tool, tooldir, ctx=self, with_sys_path=with_sys_path)
-			except ImportError as e:
-				self.fatal('Could not load the Waf tool %r from %r\n%s' % (tool, sys.path, e))
 			except Exception as e:
 				self.to_log('imp %r (%r & %r)' % (tool, tooldir, funs))
 				self.to_log(traceback.format_exc())

waflib/Context.py

@@ -188,7 +188,7 @@ class Context(ctx):
 		with_sys_path = kw.get('with_sys_path', True)
 
 		for t in tools:
-			module = load_tool(t, path, with_sys_path=with_sys_path)
+			module = load_tool(t, path, self, with_sys_path=with_sys_path)
 			fun = getattr(module, kw.get('name', self.fun), None)
 			if fun:
 				fun(self)
@@ -624,7 +624,7 @@ class Context(ctx):
 			lst = self.root.find_node(waf_dir).find_node('waflib/extras').ant_glob(var)
 			for x in lst:
 				if not x.name in ban:
-					load_tool(x.name.replace('.py', ''))
+					load_tool(x.name.replace('.py', ''), ctx=self)
 		else:
 			from zipfile import PyZipFile
 			waflibs = PyZipFile(waf_dir)
@@ -640,7 +640,7 @@ class Context(ctx):
 						doban = True
 				if not doban:
 					f = f.replace('.py', '')
-					load_tool(f)
+					load_tool(f, ctx=self)
 
 cache_modules = {}
 """
@@ -703,6 +703,8 @@ def load_tool(tool, tooldir=None, ctx=None, with_sys_path=True):
 			sys.path = tooldir + sys.path
 			try:
 				__import__(tool)
+			except ImportError as e:
+				ctx.fatal('Could not load the Waf tool %r from %r\n%s' % (tool, sys.path, e))
 			finally:
 				for d in tooldir:
 					sys.path.remove(d)
@@ -721,6 +723,8 @@ def load_tool(tool, tooldir=None, ctx=None, with_sys_path=True):
 						x = None
 				else: # raise an exception
 					__import__(tool)
+			except ImportError as e:
+				ctx.fatal('Could not load the Waf tool %r from %r\n%s' % (tool, sys.path, e))
 			finally:
 				if not with_sys_path:
 					sys.path.remove(waf_dir)