scripts/cp-noerror: Add a special copy function to fix autotools issues

Currently we copy the aclocal directory to the build so that autotools
doesn't see .m4 files disappear when its processing them. This can happen
if for example, package X is being rebuilt at the same time as Y and it
gets uninstalled from sstate (assuming there are no dependencies between
X and Y). This code making the copy was added to avoid races but introduces
a race of its own, namely that the files can disappear during the copy.

This patch adds a cp-noerror script which silently ignores such errors
and gives the behaviour we need in this case. It hence fixes issues which
crop up for users and the autobuilder occasionally.

[YOCTO #2485]

(From OE-Core rev: 0f81fbc0df73675aeb79c724858799a3b6a02f85)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/autotools.bbclass

@@ -124,10 +124,9 @@ autotools_do_configure() {
 			# uninstalling data from the sysroot. See Yocto #861 for details.
 			# We avoid this by taking a copy here and then files cannot disappear.
 			if [ -d ${STAGING_DATADIR}/aclocal ]; then
-				mkdir -p ${B}/aclocal-copy/
 				# for scratch build this directory can be empty
 				# so avoid cp's no files to copy error
-				cp -r ${STAGING_DATADIR}/aclocal/. ${B}/aclocal-copy/
+				cp-noerror ${STAGING_DATADIR}/aclocal ${B}/aclocal-copy/
 				acpaths="$acpaths -I ${B}/aclocal-copy/"
 			fi
 			# autoreconf is too shy to overwrite aclocal.m4 if it doesn't look

scripts/cp-noerror

@@ -0,0 +1,15 @@
+#!/usr/bin/env python
+#
+# Allow copying of $1 to $2 but if files in $1 disappear during the copy operation,
+# don't error.
+#
+
+import sys
+import shutil
+
+try:
+    shutil.copytree(sys.argv[1], sys.argv[2])
+except shutil.Error:
+   pass
+
+