scripts: don't overwrite generated version if we're not in a git repo

scripts/generateVersion.sh

@@ -1,4 +1,13 @@
 #!/bin/sh
+
+# if the git directory doesn't exist, don't gather data to avoid overwriting, unless
+# the version file is missing altogether (otherwise compiling will fail)
+if [[ ! -d ./.git ]]; then
+    if [[ -f ./src/version.h ]]; then
+        exit 0
+    fi
+fi
+
 cp -fr ./src/version.h.in ./src/version.h
 
 HASH=${HASH-$(git rev-parse HEAD)}