II can reproduce this with the following Makefile.am (extract) under $(srcdir)/plugins:
AUTOMAKE_OPTIONS = subdir-objects
plugins_PYTHON = \ pyhello/pyhello.py
%.eog-plugin: %.eog-plugin.desktop.in $(INTLTOOL_MERGE) $(wildcard $(top_srcdir)/po/*po) ; $(AM_V_GEN)$(INTLTOOL_MERGE) $(top_srcdir)/po $< $@ -d -u -c $(top_builddir)/po/.intltool-merge-cache
Since pyhello.py doesn't generate any file during build time, no one creates $(builddir)/plugins/pyhello, and intltool-merge dies.
Basically, this happens because of the usage of intltool-merge when Makefile.am is in a parent directory of the location of the desktop file.
II can reproduce this with the following Makefile.am (extract) under $(srcdir)/plugins:
AUTOMAKE_OPTIONS = subdir-objects
plugins_PYTHON = \
pyhello/pyhello.py
%.eog-plugin: %.eog-plugin. desktop. in $(INTLTOOL_MERGE) $(wildcard $(top_srcdir) /po/*po) ; $(AM_V_ GEN)$(INTLTOOL_ MERGE) $(top_srcdir)/po $< $@ -d -u -c $(top_builddir) /po/.intltool- merge-cache
Since pyhello.py doesn't generate any file during build time, no one creates $(builddir) /plugins/ pyhello, and intltool-merge dies.
Basically, this happens because of the usage of intltool-merge when Makefile.am is in a parent directory of the location of the desktop file.