Windows port: Monkeypatch os.path.join

But only when executing in a MinGW/MSYS context.
This ensures backslashes are automatically replaced
by forward slashed so we don't trip up MSYS quoting
rules.

https://bugzilla.gnome.org/show_bug.cgi?id=620566

giscanner/scannermain.py

@@ -382,6 +382,9 @@ def scanner_main(args):
         # on each Popen/call/check_call invocation
         subprocess.Popen = utils.MsysPopen
 
+        # Monkeypatch os.path.join so '\\' separators are replaced with '/'
+        os.path.join = utils.msysjoin
+
     parser = _get_option_parser()
     (options, args) = parser.parse_args(args)
 

giscanner/utils.py

@@ -145,3 +145,8 @@ class MsysPopen(_Popen):
     def __init__(self, args, **kwargs):
         newargs = ['sh.exe', '-c', ' '.join(args)]
         return _Popen.__init__(self, newargs, **kwargs)
+
+_join = os.path.join
+def msysjoin(a, *p):
+    path = _join(a, *p).replace('\\', '/')
+    return path