kpatch-build: fix setlocalversion for pre-v6.3 kernels

Commit 629b5ac ("kpatch-build: fix setlocalversion for pre-v6.3
kernels"), fixed VERMAGIC_STRING between kpatch original/patched kernel
builds by creating a temporary scripts/setlocalversion script.	This was
accomplished by saving the output from `make kernelversion` into a
KERNELVERSION environment variable and running the (original)
scripts/setlocalversion to gather a "vX.Y" + "<src version>" pair of
strings.

Unfortunately pre-v6.3 scripts/setlocalversion does not use the
KERNELVERSION environment variable, so the same efforts results in an
unusable "<NULL>" + "<src version>" version string pair.

Restore the original `scripts/setlocalversion --save-scmversion`
invocation for source trees that (still) support the --save-scmversion
option.

Fixes: 629b5ac ("kpatch-build: fix setlocalversion for pre-v6.3 kernels")
Signed-off-by: Joe Lawrence <[email protected]>

kpatch-build/kpatch-build

@@ -210,6 +210,8 @@ restore_kernel_files() {
 }
 
 cleanup() {
+	rm -f "$BUILDDIR/.scmversion"
+
 	remove_patches
 	restore_kernel_files
 
@@ -1118,18 +1120,23 @@ fi
 # appended to the kernel version string (VERMAGIC_STRING), even if the original
 # kernel was not dirty.  That can complicate both the build (create-diff-object
 # false positive changes) and the patch module link (module version mismatch
-# load failures).
+# load failures).  Before making any changes to the source:
+#
+# For pre-v6.3 kernels:
+# Run `./scripts/setlocalversion --save-scmversion`.
 #
-# Prevent that by replacing the original setlocalversion with a friendlier one
-# which just echo's the original version.  This should be done before any
-# changes to the source.
+# For v6.3+ kernels:
+# Replace the original setlocalversion with a friendlier one which just echo's
+# the original version.
 if [[ -n "$USERSRCDIR" && -e "$KERNEL_SRCDIR/.git" ]]; then
 	cd "$KERNEL_SRCDIR" || die
-	backup_kernel_file "scripts/setlocalversion"
-	LOCALVERSION="$(make kernelversion)"
-	LOCALVERSION="$(KERNELVERSION="$LOCALVERSION" ./scripts/setlocalversion)"
-	[[ -n "$LOCALVERSION" ]] || die "setlocalversion failed"
-	echo "echo $LOCALVERSION" > scripts/setlocalversion
+	if ! ./scripts/setlocalversion --save-scmversion &>/dev/null; then
+		backup_kernel_file "scripts/setlocalversion"
+		LOCALVERSION="$(make kernelversion)"
+		LOCALVERSION="$(KERNELVERSION="$LOCALVERSION" ./scripts/setlocalversion)"
+		[[ -n "$LOCALVERSION" ]] || die "setlocalversion failed"
+		echo "echo $LOCALVERSION" > scripts/setlocalversion
+	fi
 fi
 
 # kernel option checking