[gnome-builder] Revert "cargo: fix format for cargo arguments"

[Christian Hergert <chergert src gnome org>]

commit c4038bb000b75f1cd097b5f1ebdd47f72ca5e38c
Author: Christian Hergert <chergert redhat com>
Date:   Mon Feb 18 12:01:22 2019 -0800

    Revert "cargo: fix format for cargo arguments"
    
    This reverts commit 7e2fa0a92ca01f638ead822951352f1e1cd269a8.

 src/plugins/cargo/cargo_plugin.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/plugins/cargo/cargo_plugin.py b/src/plugins/cargo/cargo_plugin.py
index 3855f67a1..ea2b6e5e9 100644
--- a/src/plugins/cargo/cargo_plugin.py
+++ b/src/plugins/cargo/cargo_plugin.py
@@ -133,7 +133,8 @@ class CargoPipelineAddin(Ide.Object, Ide.PipelineAddin):
         build_launcher.push_argv('--')
         build_launcher.push_argv('--error-format')
         build_launcher.push_argv('short')
-        build_launcher.push_argv('--remap-path-prefix=%s' % pipeline.get_srcdir())
+        build_launcher.push_argv('--remap-path-prefix')
+        build_launcher.push_argv('=' + pipeline.get_srcdir())
 
         clean_launcher = pipeline.create_launcher()
         clean_launcher.setenv('CARGO_TARGET_DIR', builddir, True)