diff --git a/build-py-project-within-miniconda.sh b/build-py-project-within-miniconda.sh
index d7520545a7415d13ff4c957b3c5abd671c205bd8..304df8faea14a4666f59a7f2cd5418aa3ce54ab7 100644
--- a/build-py-project-within-miniconda.sh
+++ b/build-py-project-within-miniconda.sh
@@ -15,6 +15,13 @@ echo "-----------------------------------------------"
 
 # keep this consistent in build-py-project.sh and build-py-project-within-miniconda.sh
 
+# Append --editable to PROJECT_INSTALL_FLAGS, if not there already.
+# See: https://gitlab.tiker.net/inducer/ci-support/-/issues/3
+# Can be removed after pip 20.1 is released.
+if [[ ! $PROJECT_INSTALL_FLAGS =~ (^|[[:space:]]*)(--editable|-e)[[:space:]]*$ ]]; then
+    PROJECT_INSTALL_FLAGS="$PROJECT_INSTALL_FLAGS --editable"
+fi
+
 rm -Rf .env
 rm -Rf build
 find . -name '*.pyc' -delete
diff --git a/build-py-project.sh b/build-py-project.sh
index caa68394be5a916450070e0ec76ba7c52f44f73a..fa6ced9d9f3faafb0334321aa2bea3d39648d714 100644
--- a/build-py-project.sh
+++ b/build-py-project.sh
@@ -13,6 +13,13 @@ echo "-----------------------------------------------"
 
 # keep this consistent in build-py-project.sh and build-py-project-within-miniconda.sh
 
+# Append --editable to PROJECT_INSTALL_FLAGS, if not there already.
+# See: https://gitlab.tiker.net/inducer/ci-support/-/issues/3
+# Can be removed after pip 20.1 is released.
+if [[ ! $PROJECT_INSTALL_FLAGS =~ (^|[[:space:]]*)(--editable|-e)[[:space:]]*$ ]]; then
+    PROJECT_INSTALL_FLAGS="$PROJECT_INSTALL_FLAGS --editable"
+fi
+
 rm -Rf .env
 rm -Rf build
 find . -name '*.pyc' -delete