Comment # 1 on bug 1185572 from Dominique Leuenberger

Assigning to Dirk, who did the update.

Tracked it down a bit already:

Upstream's change

https://github.com/tmux/tmux/commit/d53e1fedd595db68a4e5bc9e3e7024fa924300d3

Adjusted how the socket location is being defined

 #define TMUX_SOCK "$TMUX_TMPDIR:" _PATH_TMP

then later does
     expand_paths(TMUX_SOCK, &paths, &n);
     xasprintf(&base, "%s/tmux-%ld", path, (long)uid);

We have a patch though (was rebased for 3.2) that does:

-    xasprintf(&base, "%s/tmux-%ld", path, (long)uid);
+    xasprintf(&base, "/run/tmux/%ld", (long)uid);


Which means we no hardcode /run/tmux/%ld - without a chance to override it from
outside via TMUX_TMPDIR