solenv: handle error code from ./g

This avoids "Cannot find the git binary! Is git installed and is in
PATH?" strings in the about dialog when building from a tarball.

solenv/bin/modules/installer/scriptitems.pm

@@ -815,8 +815,8 @@ sub replace_setup_variables
 
     if ( $localbuild =~ /^\s*(\w+?)(\d+)\s*$/ ) { $localbuild = $2; }   # using "680" instead of "src680"
 
-    my $buildidstring = `$ENV{'SRC_ROOT'}/g -s log -n 1 --pretty=format:%h- ; git describe --abbrev=0`;
-    if (!$buildidstring) {
+    my $buildidstring = `$ENV{'SRC_ROOT'}/g -s log -n 1 --pretty=format:%h- && git describe --abbrev=0`;
+    if ($? || !$buildidstring) {
         $buildidstring = $localbuild . $localminor . "(Build:" . $installer::globals::buildid . ")";
     }
     else {