Make 'tools/build.py -h' warn the user to run it from the repo root.

tools/build.py

Index: tools/build.py
diff --git a/tools/build.py b/tools/build.py
index 4ca626230520a00ca8122fdd4e0705ea7fde9ace..2040529968793656c5c6b402a49d80c387580758 100755
--- a/tools/build.py
+++ b/tools/build.py
@@ -511,6 +511,13 @@ def BuildCrossSdk(options, target_os, mode, arch):
 
 
 def Main():
+  # Change current directory to the repo root: the rest of this script
+  # assumes it is running from the repo root.
+  this_script = os.path.abspath(__file__)
+  this_dir = os.path.dirname(this_script)
+  repo_root = os.path.join(this_dir, os.path.pardir)
+  os.chdir(repo_root)

[zra, 2014/09/15 20:31:40]

instead maybe:
if os.getcwd() != utils.DART_DIR:
  os.chdir(utils.DART_DIR)

[Nathan Collins, 2014/09/16 01:05:08]

Yes, that's much simpler! I don't see the point of checking if we need to cd
before cd-ing, so I also dropped the check and went with simply:

os.chdir(utils.DART_DIR)

+
   utils.ConfigureJava()
   # Parse the options.
   parser = BuildOptions()