minimal/do: don't create a .did file until after a file is actually built.

With the new "continue" feature on by default, it turned out that
ctrl-c during a build, or a .do file returning an error, would mark a
target as "built" even though it hadn't been.  This would prevent
retrying it when you started minimal/do again.  Use a temp file
instead.

It's a little tricky: to prevent accidental recursion, we want to
create a file *before* building, but clean up that file when starting
the next session.  And we rename that file to the actual .did file
*after* building successfully.

t/201-fail/.gitignore

@@ -1 +1,3 @@
 /fail
+/want-fail
+/maybe-fail

t/201-fail/all.do

@@ -4,7 +4,6 @@ rm -f this-doesnt-exist
 redo-ifcreate this-doesnt-exist >/dev/null 2>&1 || exit 34  # expected to pass
 
 
-
 rm -f fail
 ! redo-ifchange fail >/dev/null 2>&1 || exit 44  # expected to fail
 
@@ -16,3 +15,14 @@ redo-ifchange fail >/dev/null 2>&1 || exit 55  # expected to pass
 # Make sure we don't leave this lying around for future runs, or redo
 # might mark it as "manually modified" (since we did!)
 rm -f fail
+
+rm -f maybe-fail
+: >want-fail
+! redo-ifchange maybe-fail >/dev/null 2>&1 || exit 66
+rm -f want-fail
+../flush-cache
+redo-ifchange maybe-fail || exit 67  # failed last time, must retry
+: >want-fail
+../flush-cache
+redo-ifchange maybe-fail || exit 68  # passed last time, no dep, no redo
+rm -f want-fail

t/201-fail/clean.do

@@ -1 +1 @@
-rm -f fail *~ .*~
+rm -f fail maybe-fail want-fail *~ .*~

t/201-fail/maybe-fail.do

@@ -0,0 +1,2 @@
+[ -e 'want-fail' ] && exit 1
+echo x

t/360-symlinks/.gitignore

@@ -1,4 +1,4 @@
-*.did
+*.ran
 *.extra
 a
 b

t/360-symlinks/a.do

@@ -1,4 +1,4 @@
-echo x >>a.did
+echo x >>a.ran
 rm -f $2.extra
 echo foo >$2.extra
 ln -s $2.extra $3

t/360-symlinks/all.do

@@ -1,14 +1,14 @@
-rm -f a a.extra b b.did
+rm -f a a.extra b b.ran
 d0=""
 redo a
 redo-ifchange b
-d1=$(cat b.did)
+d1=$(cat b.ran)
 [ "$d0" != "$d1" ] || exit 11
 
 # b only rebuilds if a changes
 ../flush-cache
 redo-ifchange b
-d2=$(cat b.did)
+d2=$(cat b.ran)
 [ "$d1" = "$d2" ] || exit 12
 
 . ../skip-if-minimal-do.sh
@@ -20,7 +20,7 @@ d2=$(cat b.did)
 ../flush-cache
 redo a
 redo-ifchange b
-d3=$(cat b.did)
+d3=$(cat b.ran)
 [ "$d2" != "$d3" ] || exit 13
 
 # Explicitly check that changing a's symlink target (a.extra) does *not*
@@ -30,5 +30,5 @@ d3=$(cat b.did)
 ../flush-cache
 touch a.extra
 redo-ifchange b
-d4=$(cat b.did)
+d4=$(cat b.ran)
 [ "$d3" = "$d4" ] || exit 14

t/360-symlinks/b.do

@@ -1,3 +1,3 @@
-echo x >>b.did
+echo x >>b.ran
 redo-ifchange a
 cat a >$3

t/360-symlinks/clean.do

@@ -1 +1 @@
-rm -f *~ .*~ a b *.extra *.did
+rm -f *~ .*~ a b *.extra *.ran