05/07: inferior: Fix concurrent cached-profile calls.

[guix-commits]

mothacehe pushed a commit to branch master
in repository guix.

commit 6ee7e3d26b8f5d2a234518cc2ab1bfeba7cd7c18
Author: Mathieu Othacehe <othacehe@gnu.org>
AuthorDate: Fri Mar 5 12:49:06 2021 +0100

    inferior: Fix concurrent cached-profile calls.
    
    * guix/inferior.scm (cached-profile): Do not create the profile symlink if 
it
    already exists.
---
 guix/inferior.scm | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/guix/inferior.scm b/guix/inferior.scm
index 714e1e1..d0cd1cc 100644
--- a/guix/inferior.scm
+++ b/guix/inferior.scm
@@ -755,8 +755,9 @@ seconds.  This procedure opens a new connection to the 
build daemon."
             (built-derivations (list profile))
             ;; Note: Caching is fine even when AUTHENTICATE? is false because
             ;; we always call 'latest-channel-instances?'.
-            (symlink* (derivation->output-path profile) cached)
-            (add-indirect-root* cached)
+            (unless (file-exists? cached)
+              (symlink* (derivation->output-path profile) cached)
+              (add-indirect-root* cached))
             (return cached))))))
 
 (define* (channels->cached-profile store channels