Flip SCons st_mtime usage back to tuple index

A previous change proposed flipping all of the Python stat references
from the older tuple index style (st[stat.ST_XXX]) to the more modern stat
structure references (st.st_xxx). This change rolls back the one place in
the actual SCons code (in Node/FS) that used the stat mtime attribute.
There's a small chance that switching scons versions back and forth
could cause some time comparison issues, since st_mtime is a float,
but for backwards compatibility reasons with ancient Python 2 versions
Python retained the integer behavior of the index form.  While problems
from this seem a low probability, avoid the issue for now.

Signed-off-by: Mats Wichmann <[email protected]>

SCons/Node/FS.py

@@ -762,7 +762,9 @@ def getmtime(self):
         st = self.stat()
 
         if st:
-            return st.st_mtime
+            # TODO: switch to st.st_mtime, however this changes granularity
+            #    (ST_MTIME is an int for backwards compat, st_mtime is float)
+            return st[stat.ST_MTIME]
         else:
             return None
 

SCons/Node/FSTests.py

@@ -774,7 +774,8 @@ def test_update(self) -> None:
 
         ni.update(fff)
 
-        mtime = st.st_mtime
+        # TODO: flip this to st.st_mtime when Node/FS.py does
+        mtime = st[stat.ST_MTIME]
         assert ni.timestamp == mtime, (ni.timestamp, mtime)
         size = st.st_size
         assert ni.size == size, (ni.size, size)
@@ -786,7 +787,8 @@ def test_update(self) -> None:
 
         st = os.stat('fff')
 
-        mtime = st.st_mtime
+        # TODO: flip this to st.st_mtime when Node/FS.py does
+        mtime = st[stat.ST_MTIME]
         assert ni.timestamp != mtime, (ni.timestamp, mtime)
         size = st.st_size
         assert ni.size != size, (ni.size, size)