https://code.monotone.ca/p/monotone/issues/180/
--- test/extra/bash_completion/bashrc	2011-09-07 09:00:12 +0000
+++ test/extra/bash_completion/bashrc	2011-09-07 12:14:59 +0000
@@ -18,6 +18,13 @@
 	. /etc/bash_completion
     elif [ -f /usr/local/etc/bash_completion ]; then
 	. /usr/local/etc/bash_completion
+    elif [ -f /usr/share/bash-completion/.pre -a \
+            -f /usr/share/bash-completion/base ]; then
+        # In Gentoo /etc/profile.d/bash-completion.sh sources required
+        # functions only if enabled with `eselect bashcomp`. We source
+        # required definitions manually.
+        source /usr/share/bash-completion/.pre
+        source /usr/share/bash-completion/base
     else
 	echo No bash completion package present.
 	exit