Mingw python has a different os.path setup from native python, and has
os.sep and os.altsep reversed. In that case, the normsep function was
doing the wrong thing, leading to all sorts of problems.
While fixing this, also ensure the corresponding unit test covers this
peculiarity, even when running under the native win32 python.
Generally speaking, the configuration needs forward-slashes in paths.
We might as well make it hard(er) to set configuration items with
backslash separators on Windows by exposing mozpath.* functions in place
of os.path functions. The downside is that functions explicitly
importing os will still get the real os.path functions.
The regular expression cache for mozpack.path.match was keyed off the
original pattern. However, that variable was mutated as part of the
function and the mutated result was subsequently stored as the cache
key. This effectively resulted in a 0% cache hit rate.
On some tests being written for bug 1132111 which involve a full
filesystem traversal for moz.build files and subsequent execution of
those files, the following timings are indicative of the impact of this
patch.
Before:
real 16.082s
user 14.760s
sys 1.318s
After:
real 6.345s
user 5.085s
sys 1.257s
