diff --git a/fdroidserver/build.py b/fdroidserver/build.py
index 021e1041..12cc61c1 100644
--- a/fdroidserver/build.py
+++ b/fdroidserver/build.py
@@ -1001,6 +1001,15 @@ def main():
     global options, config
 
     options, parser = parse_commandline()
+
+    metadata_files = glob.glob('.fdroid.*[a-z]')  # ignore files ending in ~
+    if len(metadata_files) > 1:
+        raise FDroidException("Only one local metadata file allowed! Found: "
+                              + " ".join(metadata_files))
+
+    if not os.path.isdir('metadata') and len(metadata_files) == 0:
+        raise FDroidException("No app metadata found, nothing to process!")
+
     if not options.appid and not options.all:
         parser.error("option %s: If you really want to build all the apps, use --all" % "all")
 
diff --git a/fdroidserver/common.py b/fdroidserver/common.py
index 120ef2aa..0463db29 100644
--- a/fdroidserver/common.py
+++ b/fdroidserver/common.py
@@ -157,6 +157,8 @@ def fill_config_defaults(thisconfig):
                         thisconfig['java_paths'][m.group(1)] = d
 
     for java_version in ('7', '8', '9'):
+        if java_version not in thisconfig['java_paths']:
+            continue
         java_home = thisconfig['java_paths'][java_version]
         jarsigner = os.path.join(java_home, 'bin', 'jarsigner')
         if os.path.exists(jarsigner):
diff --git a/fdroidserver/signindex.py b/fdroidserver/signindex.py
index 82f2216a..1d0c3200 100644
--- a/fdroidserver/signindex.py
+++ b/fdroidserver/signindex.py
@@ -40,7 +40,7 @@ def main():
 
     config = common.read_config(options)
 
-    if not 'jarsigner' in config:
+    if 'jarsigner' not in config:
         logging.critical('Java jarsigner not found! Install in standard location or set java_paths!')
         sys.exit(1)
 
diff --git a/hooks/pre-commit b/hooks/pre-commit
index d33c7018..6dd0049d 100755
--- a/hooks/pre-commit
+++ b/hooks/pre-commit
@@ -83,13 +83,13 @@ else
 	err "pep8 is not installed!"
 fi
 
-if [ ! -z $PY_FILES $PY_TEST_FILES ]; then
+if [ "$PY_FILES $PY_TEST_FILES" != " " ]; then
     if ! $PYFLAKES $PY_FILES $PY_TEST_FILES; then
 	err "pyflakes tests failed!"
     fi
 fi
 
-if [ ! -z $PY_FILES ]; then
+if [ "$PY_FILES" != "" ]; then
     if ! $PEP8 --ignore=$PEP8_IGNORE $PY_FILES; then
 	err "pep8 tests failed!"
     fi
@@ -98,7 +98,7 @@ fi
 # The tests use a little hack in order to cleanly import the fdroidserver
 # package locally like a regular package.  pep8 doesn't see that, so this
 # makes pep8 skip E402 on the test files that need that hack.
-if [ ! -z $PY_TEST_FILES ]; then
+if [ "$PY_TEST_FILES" != "" ]; then
     if ! $PEP8 --ignore=$PEP8_IGNORE,E402 $PY_TEST_FILES; then
 	err "pep8 tests failed!"
     fi
diff --git a/tests/run-tests b/tests/run-tests
index c770091f..7629f431 100755
--- a/tests/run-tests
+++ b/tests/run-tests
@@ -156,6 +156,41 @@ fi
 set -e
 
 
+#------------------------------------------------------------------------------#
+echo_header "ensure commands that don't need the JDK work without a JDK configed"
+
+REPOROOT=`create_test_dir`
+cd $REPOROOT
+mkdir repo
+mkdir metadata
+echo "License:GPL" >> metadata/fake.txt
+echo "Summary:Yup still fake" >> metadata/fake.txt
+echo "Categories:Internet" >> metadata/fake.txt
+echo "Description:" >> metadata/fake.txt
+echo "this is fake" >> metadata/fake.txt
+echo "." >> metadata/fake.txt
+
+# fake that no JDKs are available
+echo 'java_paths = {}' > config.py
+
+LOCAL_COPY_DIR=`create_test_dir`/fdroid
+mkdir -p $LOCAL_COPY_DIR/repo
+echo "local_copy_dir = '$LOCAL_COPY_DIR'" >> config.py
+
+$fdroid checkupdates
+$fdroid gpgsign
+$fdroid lint
+$fdroid readmeta
+$fdroid rewritemeta fake
+$fdroid server update
+$fdroid scanner
+
+# run these to get their output, but the are not setup, so don't fail
+$fdroid build || true
+$fdroid import || true
+$fdroid install || true
+
+
 #------------------------------------------------------------------------------#
 echo_header "create a source tarball and use that to build a repo"