[beast: 9/23] BUILD: only generate shortened ChangeLog if the limiting commits are known

[Tim Janik <timj src gnome org>]

commit da25604e632d341565a89ddc66e2ed7991ec5557
Author: Tim Janik <timj gnu org>
Date:   Wed Oct 7 22:27:37 2015 +0200

    BUILD: only generate shortened ChangeLog if the limiting commits are known
    
    Avoid travis-ci bailing out during ChangeLog generation, because we
    unconditionally refer to a commint that's been pruned from history
    during travis' repository cloning.
    
    Signed-off-by: Tim Janik <timj gnu org>

 Makefile.am |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 51344ed..36c49ff 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -44,10 +44,12 @@ test_option = test `echo ":$(strip $(1)):" | sed 's/.*:$(strip $(2))://g' | wc -
       `echo ":$(strip $(1)):" | sed 's/.*:$(or $(strip $(3)), no-$(strip $(2)))://g' | wc -c`
 
 # == ChangeLog & Release Rules ==
+CHANGELOG_RANGE = $(shell git cat-file -e ce584d04999a7fb9393e1cfedde2048ba73e8878 && \
+                   echo ce584d04999a7fb9393e1cfedde2048ba73e8878..HEAD || echo HEAD)
 ChangeLog: $(GITSTAMPS)
        $(AM_V_GEN)
-       $(Q) git log --date=short --pretty='^^%ad  %an  # %h%n%n%B%n' --abbrev=11 --first-parent \
-               ce584d04999a7fb9393e1cfedde2048ba73e8878..HEAD   > xgen-$(@F) # Generate ChangeLog with 
^^-prefixed records
+       $(Q) git log --pretty='^^%ad  %an       # %h%n%n%B%n' --abbrev=11 \
+               --date=short --first-parent $(CHANGELOG_RANGE)   > xgen-$(@F) # Generate ChangeLog with 
^^-prefixed records
        $(Q) sed 's/^/  /; s/^  ^^// ; s/[[:space:]]\+$$// '    -i xgen-$(@F) # Tab-indent commit bodies, 
kill trailing whitespaces
        $(Q) sed '/^\s*$$/{ N; /^\s*\n\s*$$/D }'                -i xgen-$(@F) # Compress multiple newlines
        $(Q) mv xgen-$(@F) $@