Modify rhel8-support.sh to handle Fedora as well, and rename it

I renamed the file to mangle-shebangs.sh, since it is no longer
specific to RHEL8.  I also changed Makefile to call mangle-shebangs.sh
instead of rhel8-support.sh

Makefile

@@ -45,9 +45,9 @@ specfile: clean
 .PHONY: sources
 sources: tarball specfile
 
-.PHONY: rhel8-support
-rhel8-support:
-	./rhel8-support.sh
+.PHONY: shebang-support
+shebang-support:
+	./mangle-shebangs.sh
 
 .PHONY: rpm-only
 rpm-only:
@@ -58,7 +58,7 @@ rpm-only:
 	cp $(BUILD_DIR)/RPMS/*/*rpm build
 
 .PHONY: rpm
-rpm: rhel8-support sources rpm-only
+rpm: shebang-support sources rpm-only
 
 .PHONY: deb
 deb:

rhel8-support.sh → mangle-shebangs.sh

 #!/bin/bash
 
 SYSTEM_RELEASE_PATH=/etc/system-release
+RHEL8_REGEX="Red Hat Enterprise Linux release 8"
+FEDORA_REGEX="Fedora release"
 
-if [ -f $SYSTEM_RELEASE_PATH ] && [[ "$(cat $SYSTEM_RELEASE_PATH)" =~ "Red Hat Enterprise Linux release 8" ]]; then
-    # Replace the first line in .py to "#!/usr/bin/env python2" no matter what it was before
+# RHEL8 and Fedora30+ both treat shebangs of the form "#!/usr/bin/env python" as errors
+if [ -f $SYSTEM_RELEASE_PATH ] && [[ "$(cat $SYSTEM_RELEASE_PATH)" =~ $RHEL8_REGEX|$FEDORA_REGEX ]]; then
+    # Replace the first line in .py to "#!/usr/bin/env python2" no
+    # matter what it was before
     sed -i -e '1 s/^.*$/\#!\/usr\/bin\/env python2/' src/watchdog/__init__.py
     sed -i -e '1 s/^.*$/\#!\/usr\/bin\/env python2/' src/mount_efs/__init__.py
 fi