A recent tmux update in F26 broke tmuxinator for me. Upstream tmux fixed the bug, but the fix will be released in 2.6. I wanted to avoid being stuck with 2.3, so I backported the (very short) patch and applied it against tmux-2.5. I verified that it works.

double check:
--- tmux.spec.orig	2017-07-31 11:09:39.401580626 -0400
+++ tmux.spec	2017-07-31 11:18:16.000000000 -0400
@@ -1,6 +1,6 @@
 Name:           tmux
 Version:        2.5
-Release:        1%{?dist}
+Release:        2%{?dist}
 Summary:        A terminal multiplexer
 
 Group:          Applications/System
@@ -13,6 +13,12 @@
 # Examples has been removed - so include the bash_completion here
 Source1:        bash_completion_tmux.sh
 
+# tmuxinator wouldn't start with tmux 2.5
+# tmuxinator discussion: https://github.com/tmuxinator/tmuxinator/issues/536
+# tmux discussion (states that the patch won't be backported to 2.5):
+#  https://github.com/tmux/tmux/issues/971  
+Patch0:         tmux-2.5-fail-on-no-target.diff
+
 BuildRequires:  ncurses-devel
 BuildRequires:  libevent-devel
 BuildRequires:  libutempter-devel
@@ -24,7 +30,7 @@
 as GNU Screen.
 
 %prep
-%setup -q
+%autosetup
 
 %build
 CFLAGS="$RPM_OPT_FLAGS -fPIC -pie -Wl,-z,relro -Wl,-z,now"