Fix problem with Install and multiple dirs outside src tree.

In some cases it's possible to get a case where the target
path already does exist, but the dir node for it hasn't been
updated yet. This fix prevents MkdirFunc from trying to create
it when it already exists. Added a testcase which failed before
the fix and works after it.

Also fixes a problem running tests on Windows, using standard
python 3 which is installed in "C:/Program Files/Python36".
The python path name has to be escaped in that case. See runtest.py.

1 files changed, 6 insertions, 1 deletions

diff --git a/src/engine/SCons/Node/FS.py b/src/engine/SCons/Node/FS.py
index 684f0d1..9a48432 100644
--- a/src/engine/SCons/Node/FS.py
+++ b/src/engine/SCons/Node/FS.py
@@ -328,7 +328,12 @@ Unlink = SCons.Action.Action(UnlinkFunc, None)
 
 def MkdirFunc(target, source, env):
     t = target[0]
-    if not t.exists():
+    # This os.path.exists test looks redundant, but it's possible
+    # when using Install() to install multiple dirs outside the
+    # source tree to get a case where t.exists() is true but
+    # the path does already exist, so this prevents spurious
+    # build failures in that case. See test/Install/multi-dir.
+    if not t.exists() and not os.path.exists(t.get_abspath()):
         t.fs.mkdir(t.get_abspath())
     return 0